Showing papers in "Journal of Biochemistry in 1984"

Detection of calcium binding proteins by 45Ca autoradiography on nitrocellulose membrane after sodium dodecyl sulfate gel electrophoresis.

Abstract: A new simple method of detecting calcium binding proteins in a protein mixture is described. A sample which might include calcium binding proteins was subjected to SDS-polyacrylamide gel electrophoresis and then electrophoretically transferred to a nitrocellulose membrane. The membrane was then incubated with 45Ca to detect calcium binding proteins as radioactive bands by autoradiography. Purified troponin-C, calmodulin, myosin DTNB light chain, and parvalbumin were clearly identified by this method. In the whole homogenate of chicken skeletal muscle, myosin DTNB light chain, troponin-C, and 55K calcium binding protein were found to be radioactive. In the frog skeletal muscle, small molecular weight proteins of approximately 13-15K and 70K protein appeared to be the calcium binding proteins. In the case of the carp skeletal muscle, small molecular weight proteins including parvalbumin and two proteins of about 80K seemed to bind calcium ion. Two high molecular weight calcium binding proteins were present in the scallop striated muscle. The procedure described can be completed within 24 h and can detect as little as 2 micrograms of calcium binding protein in the starting sample. Under appropriate conditions it was possible to detect only high affinity calcium binding proteins.

Reexamination of the pyridylamination used for fluorescence labeling of oligosaccharides and its application to glycoproteins.

Abstract: The pyridylamination reaction of sugar chains from glycoproteins was re-investigated to raise the total yield of pyridylamino sugars. Sugar chains of glycoproteins were released by hydrazinolysis, and free amino groups were N-acetylated. The sugar chains were coupled with 2-aminopyridine, and the pyridylamino derivatives thus obtained were purified by Sephadex G-15 column chromatography and analyzed by high performance liquid chromatography. In this study, conditions for the coupling reaction (temperature, time, pH, concentration of 2-aminopyridine, and amount of the reducing reagent) were re-investigated. Under the conditions established in the present study, the total recovery of pyridylamino derivatives of sugar chains of glycoproteins was about 70%, and 0.15 nmol of a glycoprotein was enough to detect the pyridylamino derivatives of sugar chains. The stability of sialyl and fucosyl linkages under the present conditions was also studied.

Nucleotide sequence of the tobacco mosaic virus (tomato strain) genome and comparison with the common strain genome.

Abstract: The sequence of about 4,500 nucleotides of the internal part of tobacco mosaic virus (TMV)-tomato strain (L) RNA has been newly determined using cloned cDNAs. Together with the previously determined partial sequences at both ends, the entire sequence of the 6,384 nucleotide genome has been completed. The 130K (1,115 amino acids), 180K (1,615 amino acids), 30K (263 amino acids) and coat protein (158 amino acids) cistrons are located at residues 72-3442, 72-4922, 4906-5700, and 5703-6182 on the genome, respectively. Sequence polymorphism was not observed except for heterogeneity in the length of the A cluster near the 3' end. The homology of the nucleotide sequences of TMV-L and TMV-vulgare, a common strain, is about 80% on average. Remarkable differences between them were found in a part of the N-terminal portion of the 130K/180K protein and the C-terminal portion of the 30K protein. A new method for cDNA cloning was developed by which the cDNA of the 5'-terminus of viral RNA can be cloned efficiently.

Molecular size and shape of beta-connectin, an elastic protein of striated muscle.

Abstract: Connectin is an elastic protein of vertebrate striated muscle, and consists of doublet components, alpha and beta (also called titins 1 and 2). In the present study, beta-connectin isolated in the native state was investigated in order to characterize its molecular size and shape. The molecular weight was approximately 2.1 X 10(6) (SDS gel electrophoresis) or 2.7 X 10(6) (sedimentation equilibrium). The sedimentation coefficient (SO20, w) was 17S in 0.1 M phosphate buffer, pH 7.0. The intrinsic viscosity measured in an Ostwald-type viscometer was 1.8 dl/g. However, the viscosity was greatly dependent on the velocity gradient, and at a very low velocity gradient of 0.0007 s-1, a solution of connectin (0.3 mg/ml) showed a viscosity value of 17,000 cp. Flow birefringence measurements suggested a length distribution ranging from 300 to 450 nm. Electron microscopic observations revealed that connectin is a long flexible filament and the peaks of frequency of length distribution were at 150, 300, 450, and 600 nm. It was tentatively assumed that the connectin molecule is 300-400 nm long and 34-38 nm wide. It is likely that beta-connectin is derived from alpha-connectin, which has an apparent molecular weight of 2.8 X 10(6).

Pathogenesis of Serratial Infection: Activation of the Hageman Factor-Prekallikrein Cascade by Serratial Protease

Abstract: A serratial protease with an apparent molecular weight of 56,000 (56K protease), which had been purified from the culture supernatant of a strain of Serratia marcescens isolated from a corneal lesion of a human eye [Matsumoto, K. et al. (1984) J. Bacteriol. 157, 225-232], greatly enhanced vascular permeability when injected into guinea pig skin. The 56K protease, which requires zinc ion for activity, was found to possess plasma kallikrein-like properties in vitro as judged by (i) preferential amidolysis of carbobenzoxy-Phe-Arg-4-methylcoumaryl-7-amide and Pro-Phe-Arg-4-methylcoumaryl-7-amide, which are known substrates for plasma kallikrein; (ii) release of kinin from high-molecular-weight kininogen; and (iii) prompt activation of Hageman factor followed by generation of kallikrein from plasma prekallikrein. These results suggest that the 56K protease enhances vascular permeability through activation of a Hageman factor-kallikrein-kinin pathway in vivo, and this molecular process appears to be a rational mechanism of enhancement of permeability and serratial pathogenesis.

Mechanism of Inhibition of Activated Protein C by Protein C Inhibitor

Abstract: Protein C inhibitor isolated from human plasma inhibited thrombin, factor Xa, trypsin and chymotrypsin as well as activated protein C, but had very little effect on urokinase and plasmin. The inhibition constants (K1) of protein C inhibitor for activated protein C, thrombin and factor Xa were 5.6 X 10(-8) M, 6.7 X 10(-8) M and 3.1 X 10(-7) M, respectively. The second-order rate constant for inhibition of activated protein C by the inhibitor increased about 30-fold in the presence of an optimal heparin concentration (5-10 units/ml). The inhibition of activated protein C by plasma protein C inhibitor was also accelerated by heparin. When activated protein C (Mr = 62,000) was incubated with protein C inhibitor (Mr = 57,000), enzyme-inhibitor complexes with apparent Mr = 102,000 and 88,000 were observed in the nonreduced and the reduced samples, respectively, on SDS-polyacrylamide gel electrophoresis. In addition to these complexes, a band of unbound enzyme and a band with Mr = 54,000 were detected. When 125I-labeled protein C inhibitor was exposed to activated protein C, the inhibitor band was converted to bands with apparent Mr = 102,000 and 54,000 in the nonreduced samples, as determined by autoradiography after gel electrophoresis in SDS. The band with Mr = 54,000 also appeared when the inhibitor reacted with other serine proteases. The activated protein C was released from the inactive complex by treatment with 1 M ammonia or hydroxylamine. This phenomenon was found by SDS-polyacrylamide gel electrophoresis to represent the dissociation of the enzyme-inhibitor complex by ammonia or hydroxylamine into the free enzyme and the proteolytically modified inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of digitonin and its analogs with membrane cholesterol.

Abstract: The interaction of digitonin with membrane cholesterol was studied by using various digitonin analogs, and radioactive desglucodigitonin. The following results were obtained concerning the effect of digitonin on erythrocytes, granulocytes and liposomes. Digitonin and its analogs showed activity to induce hemolysis, granulocyte activation and liposomal membrane damage. The activity was affected by change of the carbohydrate residue of the molecule; the order of hemolytic activity was digitonin greater than or equal to desglucodigitonin much greater than glucosyl-galactosyl-digitogenin greater than galactosyl-digitogenin, digitogenin. The relative activities of these compounds to induce granulocyte activation and liposomal membrane damage were similar to those observed in the hemolysis. [3H]Desglucodigitonin could bind to cholesterol in liposomes. The binding was stoichiometric and the ratio of desglucodigitonin bound to liposomes/cholesterol in liposomes was close to 1, irrespective of the cholesterol content in liposome. Damage to liposomes was, however, induced by desglucodigitonin only when they contained more than 0.2 molar ratio of cholesterol to phospholipid. Addition of digitonin as well as desglucodigitonin to preformed liposomes deprived of cholesterol affected the anisotropic molecular motion of spin-labeled phosphatidylcholine incorporated into the liposomes, suggesting that the molecules could be inserted into the lipid bilayer free of cholesterol. Molecules of desglucodigitonin in the lipid phase may, however, be equilibrated with those in the aqueous phase, unless they form a complex with cholesterol, since no appreciable amount of [3H]desglucodigitonin could be detected in the liposome fraction after separation by column chromatography. Digitonin decreased the order parameter of spin-labeled phosphatidylcholine when liposomes contained equimolar cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Cystatin S: A cysteine proteinase inhibitor of human saliva.

Abstract: An acidic protein of human saliva, which we named SAP-1 previously, is now shown to be an inhibitor of several cysteine proteinases. The protein inhibited papain and ficin strongly, and stem bromelain and bovine cathepsin C partially. However, it did not inhibit either porcine cathepsin B or clostripain. The mode of the inhibition of papain was found to be non-competitive. The name cystatin S has been proposed for this salivary protein in view of the similarities in activity and structure to other cysteine proteinase inhibitors such as chicken egg-white cystatin and human cystatins A, B, and C. The cystatin S antigen was detected immunohistochemically in the serous cells of human parotid and submaxillary glands.

Sensitive enzyme-immunostaining and densitometric determination on thin-layer chromatography of N-glycolylneuraminic acid-containing glycosphingolipids, Hanganutziu-Deicher antigens.

Abstract: A sensitive enzyme-immunochemical staining method was developed for detection of N-glycolylneuraminic acid (NeuGc)-containing glycosphingolipids (GSLs) on silica gel thin-layer chromatography. The procedure consists of immune reaction among NeuGc-containing GSLs, affinity-purified chicken anti-NeuGc-LacCer and horseradish peroxidase-conjugated rabbit anti-chicken IgG, and the peroxidase reaction using 4-chloro-1-naphthol as a chromogenic substrate. Quantitative determination was achieved by direct densitometric scanning of the enzyme-immunostained spots on the chromatogram. As little as 0.5 pmol of NeuGc-LacCer, NeuGc-nLcOse4Cer, and NeuGc-nLcOse6Cer (0.64-1.0 ng) could be detected with a good signal-to-noise ratio. A semi-linear detector response was observed up to 50 pmol of each GSL. This procedure can be applied easily to other glycolipid antigen systems.

Calcium Binding to Calmodulin: Effects of Ionic Strength, Mg2+, pH and Temperature

Abstract: To deepen our understanding of Ca2+-activation in calmodulin-dependent reactions, the properties of Ca binding to calmodulin were examined by dual-wavelength spectrophotometry using a Ca indicator, tetramethylmurexide. The Scatchard plot for Ca binding to calmodulin was linear, indicating the occurrence of homogeneous independent binding sites. The apparent binding constant of calmodulin for Ca2+ (K) was (1.96 +/- 0.05) X 10(5) M-1 (20), and the number of binding sites (n) was 3.36 +/- 0.04 (20) mol/mol in reaction medium containing 100 mM KCl, 20 mM MOPS-KOH (pH 6.80), and 0.12 mM tetramethylmurexide at 20 degrees C. K was strongly dependent on the concentration of KCl, while n was independent of it. On the assumption that this is due to the effect of ionic strength (I), K may be described as follows: log K = 6.73-3.2 [2 square root I/(1 + square root I)-0.4 X I] (0.006 less than or equal to I less than or equal to 0.256, pH 6.80, at 20 degrees C). Mg2+ decreased K, which could be expressed as K/(1 + 130 [Mg] ) ( [Mg] in mol (M) ) at the ionic strength of 0.106, pH 6.80 at 20 degrees C. n was also decreased in the presence of Mg2+. This suggests that Mg2+ may have effects other than simple competition. The pH of the medium affected K or n very little at around neutral pH. This may correspond to the fact that calmodulin is an acidic protein with pI congruent to 4.3. K or n was only slightly dependent on the temperature. This corresponds to the calorimetric result that the enthalpy change on Ca binding was very slight and endothermic. Based on these findings, much of the discrepancy among the results already reported on Ca-binding can be explained. Activation of a calmodulin-dependent reaction is discussed on the basis of Ca binding to calmodulin under physiological conditions.

Purification of Human Plasma α1-Proteinase Inhibitor and Its Inactivation by Pseudomonas aeruginosa Elastase

Abstract: Human alpha 1-proteinase inhibitor was purified according to a modification of the method of Kurecki et al. (Anal. Biochem. 99, 415 (1979) ), with Affi-Gel Blue treatment before Zn-affinity column chromatography. The inhibitor was inactivated in the presence of Pseudomonas aeruginosa elastase (1/2,000 molar ratio) for 2 h at pH 7.5 and 25 degrees C. The inactivated inhibitor was purified by column chromatography on Sephadex G-75 and DE-52. Little or no difference was observed between the native and inactive inhibitors in immunological response, amino acid composition or far-ultraviolet CD spectrum. On the other hand, a considerable difference was observed in the near-ultraviolet CD spectrum. Two amino-terminal sequences were found in the inactive inhibitor in almost the same ratio; one was the same as that of the intact inhibitor and the other was Met-Ser-Ile-Pro-. The two components were separated by high-performance liquid chromatography using 0.1% trifluoroacetic acid containing 30-70% CH3CN (gradient) as the eluent. Amino acid analysis and N- and C-terminal amino acid sequence analyses indicated that one fraction corresponded to the sequence of 1-357 of the alpha 1-proteinase inhibitor and the other to 358-394. We concluded that P. aeruginosa elastase can inactivate human alpha 1-proteinase inhibitor by splitting the peptide bond of Pro357-Met358, leading to local change near the active site but little change in the structure as a whole. The split carboxy-terminal fragment binds tightly to the rest of the inhibitor.

Purification and properties of N-acetylneuraminate lyase from Escherichia coli

Abstract: N-Acetylneuraminate lyase [N-acetylneuraminic acid aldolase EC 4.1.3.3] from Escherichia coli was purified by protamine sulfate treatment, fractionation with ammonium sulfate, column chromatography on DEAE-Sephacel, gel filtration on Ultrogel AcA 44, and preparative polyacrylamide gel electrophoresis. The purified enzyme preparation was homogeneous on analytical polyacrylamide gel electrophoresis, and was free from contaminating enzymes including NADH oxidase and NADH dehydrogenase. The enzyme catalyzed the cleavage of N-acetylneuraminic acid to N-acetylmannosamine and pyruvate in a reversible reaction. Both cleavage and synthesis of N-acetylneuraminic acid had the same pH optimum around 7.7. The enzyme was stable between pH 6.0 to 9.0, and was thermostable up to 60 degrees C. The thermal stability increased up to 75 degrees C in the presence of pyruvate. No metal ion was required for the enzyme activity, but heavy metal ions such as Ag+ and Hg2+ were potent inhibitors. Oxidizing agents such as N-bromosuccinimide, iodine, and hydrogen peroxide, and SH-inhibitors such as p-chloromercuribenzoic acid and mercuric chloride were also potent inhibitors. The Km values for N-acetylneuraminic acid and N-glycolylneuraminic acid were 3.6 mM and 4.3 mM, respectively. Pyruvate inhibited the cleavage reaction competitively; Ki was calculated to be 1.0 mM. In the condensation reaction, N-acetylglucosamine, N-acetylgalactosamine, glucosamine, and galactosamine could not replace N-acetylmannosamine as substrate, and phosphoenolpyruvate, lactate, beta-hydroxypyruvate, and other pyruvate derivatives could not replace pyruvate as substrate. The molecular weight of the native enzyme was estimated to be 98,000 by gel filtration methods. After denaturation in sodium dodecyl sulfate or in 6 M guanidine-HCl, the molecular weight was reduced to 33,000, indicating the existence of 3 identical subunits. The enzyme could be used for the enzymatic determination of sialic acid; reaction conditions were devised for determining the bound form of sialic acid by coupling neuraminidase from Arthrobacter ureafaciens, lactate dehydrogenase, and NADH.

Comparison of low and high calcium requiring forms of the calcium-activated neutral protease (CANP) from rabbit skeletal muscle.

Abstract: Two distinct calcium-dependent neutral proteases (CANPs) with different sensitivities to calcium ions were purified concurrently by almost the same procedures from rabbit skeletal muscle and their enzymatic properties were compared (sensitivity to various divalent metal ions, the pH dependency and heat-stability of the activity, and the hydrolytic activity towards various substrates). They were further compared chemically in terms of the state of thiol groups, the amino acid compositions of subunits and the peptide fragments by digestion with S. aureus V8 protease. The low calcium requiring form of CANP (microCANP) was more sensitive to other divalent metal ions such as Sr2+ and Ba2+ than the high calcium requiring form of CANP (mCANP). The comparison of the pH dependency of these CANP activities showed that microCANP was active in a broader pH range than mCANP and the former was more heat-stable than the latter. Both CANPs had similar affinity to various substrates, but the hydrolytic velocity was several times higher with microCANP than with mCANP. Although they were inhibited by thiol protease inhibitors to the same extent, the states of thiol groups in them were quite different. The thiol group involved in the catalytic activity of the enzyme was exposed without adding Ca2+ in microCANP, whereas the group in mCANP became exposed only when sufficient Ca2+ was added. The large subunits of these two CANPs were different in their amino acid compositions and in the peptide fragment patterns produced by S. aureus V8 protease but the small subunits were indistinguishable from each other. These results led us to conclude that these two CANPs are quite different in nature and are not in a simple relationship, i.e., one of them is not derived from the other by autolysis or modification.

Isolation and Amino Acid Sequence of SAP-1, an Acidic Protein of Human Whole Saliva, and Sequence Homology with Human γ-Trace

Abstract: A low-molecular-weight acidic protein was isolated from human whole saliva by DE32 column chromatography and designated as SAP-1. The amino acid sequence was determined by conventional methods to be (sequence in text). The protein consisted of 113 residues and the calculated molecular weight was 12,552. Computer analysis revealed the presence of 54% sequence homology between SAP-1 and gamma-trace, a basic microprotein present in cerebrospinal fluid and in urine of patients with renal failure.

Isolation of low molecular weight actin-binding proteins from porcine brain.

Abstract: Three new actin-binding proteins having molecular weights of 26,000, 21,000, and 19,000 were isolated from porcine brain by DNase I affinity column chromatography. These proteins were released from the DNase I column by elution with a solution of high ionic strength. They were further purified by column chromatographies using hydroxyapatite, phosphocellulose, and Sephadex G-75. All of these actin-binding proteins behaved as monomeric particles in the gel filtration chromatography. After elution of the three actin-binding proteins, actin and profilin were recovered from the DNase I column with 2 M urea solution. The eluted was further purified by a cycle of polymerization and depolymerization and finally by gel filtration. Little difference in polymerizability was detected between the purified brain actin and muscle actin. After sedimentation of the polymerized brain actin, profilin was purified by DEAE-cellulose and gel filtration column chromatographies. In the assay of the action of these actin-binding proteins, the 26K protein was found to cause a large decrease in the rate of actin polymerization, while showing little effect on the extent of polymerization. The 21K protein decreased the steady-state viscosity of actin solution in a concentration-dependent manner irrespective of whether it was added before or after actin polymerization. It reacted with actin at a 1:1 molar ratio.

Different tissue distributions of two types of thiol proteinase inhibitors from rat liver and epidermis.

Abstract: The concentrations of two types of endogenous inhibitors of thiol proteinases were determined in soluble extracts of various rat tissues by means of a sensitive enzyme immunoassay method, which consisted of solid-phase immobilized anti-rat liver inhibitor or anti-rat epidermal inhibitor and antibodies labeled with horseradish peroxidase. The minimum detectable amounts of inhibitors from liver and epidermis were 30 pg and 3 pg/assay, respectively. The tissue distributions of the epidermal and liver-type inhibitors were found to differ. The liver-type inhibitor was found to be widely distributed in various tissues at levels of 76-420 ng/mg protein, whereas the epidermal-type inhibitor was found at high levels in the skin, tongue, esophagus, stomach, intestine, and vagina, but at quite low levels in other tissues tested.

Hemoprotein H-450 identified as a form of cytochrome P-450 having an endogenous ligand at the 6th coordination position of the heme.

Abstract: Hemoprotein H-450 was purified from rat liver cytosol to homogeneity by an improved procedure. The purified H-450 showed a subunit molecular weight of 64,000 daltons and contained 0.7-0.9 mol of protoheme per mol subunit. Among rat tissues examined, liver and kidney contained significant amounts of H-450 in the cytosol. Oxidized H-450 showed a Soret peak at 428 nm and a broad beta band at around 550 nm. Reduced H-450 was found to exist in two interconvertible forms, alkaline and acid forms. The alkaline form showed Soret, beta, and alpha peaks at 448, 540, and 571 nm, whereas the acid form showed Soret, beta, and alpha peaks at 425, 530, and 558 nm. The spectral properties of both oxidized and reduced H-450 in alkaline medium resemble those of cytochrome P-450 having a nitrogenous ligand at the 6th coordination position of the heme. Upon addition of low concentrations of HgCl2, H-450 was converted to a denatured form both in the oxidized and the reduced states and lost its unique spectral characteristics. Addition of carbon monoxide to reduced H-450 produced a new spectral species which resembled that of the reduced carbon monoxide complex of P-420, a denatured form of cytochrome P-450. Comparison of the EPR signal of oxidized H-450 with those of a cytochrome P-450, P-450(PB-1), and several model compounds indicated the presence of a thiolate anion at the 5th coordination position of the heme of H-450. Judging from EPR data, oxidized H-450 also converts between acid and alkaline forms, whose signals were observed at g = 1.867, 2.31, and 2.507 and at g = 1.910, 2.28, and 2.424, respectively. These lines of evidence indicate that the 5th and 6th coordination positions of the heme of H-450 are a thiolate and a nitrogenous group, respectively. With respect to the heme environments, H-450 is a member of the cytochrome P-450 family, and has a nitrogenous ligand at the 6th coordination position of the heme.

Characterization of nitrite reductase from a denitrifier, Alcaligenes sp. NCIB 11015. A novel copper protein.

Abstract: A copper-containing dissimilatory nitrite reductase [nitric-oxide: ferricytochrome c oxidoreductase, EC 1.7.2.1] was purified from a denitrifier, Alcaligenes sp. NCIB 11015, by ion-exchange chromatography on CM-cellulose, gel filtration on Sephadex G-150, and adsorption on hydroxyapatite. The preparation was homogeneous by SDS-polyacrylamide gel electrophoretic criteria, and its enzymatic activity increased considerably by freezing (at -20 degrees C) and thawing. The enzyme consists of two subunits with a molecular weight of 37,000, and the isoelectric point and redox potential are 8.4 and +260 mV (pH 7.2), respectively. The EPR spectrum and copper analysis clearly indicated that the enzyme contains two type I copper atoms per molecule but no other types of copper. This is the first blue copper protein that exhibits catalytic activity despite possessing only type I copper.

Characterization of Hen Egg White- and Yolk-Riboflavin Binding Proteins and Amino Acid Sequence of Egg White-Riboflavin Binding Protein

Abstract: White- and Yolk-riboflavin binding proteins were isolated from hen eggs, and characterized as to their chemical properties. White- and Yolk-RBPs had almost same amino acid compositions except for glutamic acid, but their carbohydrate compositions were different from each other. The complete amino acid sequence of White-RBP was determined by conventional methods. White-RBP comprised 219 amino acid residues, and the amino-terminus was pyroglutamic acid (pyrrolidonecarboxylic acid). Two amino acids, lysine and asparagine, were found at the fourteenth residue from the amino-terminus. Carbohydrate chains were linked to asparagine residues at positions 36 and 147. Both White- and Yolk-RBPs were phosphorylated. In White-RBP either six or seven of nine serine residues between Ser(185) and Ser(197) were phosphorylated. The amino acid sequences around phosphoserines showed that phosphorylation might occur at a serine residue in one of the following sequences; Ser-X-Glu or Ser-X-Ser(P).

Isolation of two novel proteinase inhibitors from hemolymph of silkworm larva, Bombyx mori. Comparison with human serum proteinase inhibitors.

Abstract: Two protein proteinase inhibitors, anti-trypsin and anti-chymotrypsin, were isolated from the hemolymph of silkworm larva, Bombyx mori, using conventional gel filtration and ion exchange chromatography techniques. They had similar physicochemical properties, in molecular weight (42,000 for anti-trypsin and 43,000 for anti-chymotrypsin), in amino acid composition, and in CD spectrum. Further comparison of these characteristics with human serum inhibitors, alpha-1-proteinase inhibitor and alpha-1-antichymotrypsin, suggested the resemblance of silkworm and human inhibitors. But the N-terminal sequences were not homologous to each other and antiserum against each silkworm inhibitor only formed a precipitin lines with its own antigen. These results indicated differences in minute parts of the inhibitors.

Calcium binding to tryptic fragments of calmodulin.

Abstract: Fragments of scallop testis calmodulin were prepared by tryptic digestion. One peptide consisted of 75 amino acid residues from N-acetylalanine to lysine at position 75 (F12) and the other of 71 residues from aspartic acid at position 78 to C-terminal lysine (F34). Flow dialysis and equilibrium dialysis experiments revealed the existence of two Ca2+ binding sites in each fragment. Half-saturating concentrations of the Ca2+ titration curves were 11 microM for F12 and 3.2 microM for F34, and Hill coefficients were obtained as 1.14 and 1.84, respectively. The results indicate that the high-affinity sites for Ca2+ are located on the C-terminal region of the calmodulin. The sum of the two Ca2+ titration curves of F12 and F34 fits well to the curves of Ca2+ binding to intact calmodulin. This shows that the characteristic of Ca2+ bindings in intact calmodulin did not change after separation of the whole molecule into two domains, F12 and F34. The domains corresponding to F12 and F34 may exist independently from each other in the intact calmodulin molecule.

Intracellular distribution of fumarase in various animals.

Abstract: The subcellular distribution of fumarase was investigated in the liver of various animals and in several tissues of the rat. In the rat liver, fumarase was predominantly located in the cytosolic and mitochondrial fractions, but not in the peroxisomal fraction. The amount of fumarase associated with the microsomes was less than 5% of the total enzyme activity. The investigation of the intracellular distribution of hepatic fumarase of the rat, mouse, rabbit, dog, chicken, snake, frog, and carp revealed that the amount of the enzyme located in the cytosol was comparable to that in the mitochondria of all these animals. The subcellular distribution of the enzyme in the kidney, brain, heart, and skeletal muscle of rat, and in hepatoma cells (AH-109A) was also investigated. Among these tissues, the brain was the only exception, having no fumarase activity in the cytosolic fraction, and the other tissues showed a bimodal distribution of fumarase in the cytosol and the mitochondria. The mitochondrial fumarase was predominantly located in the matrix. About 10% of the total fumarase was found in the outer and inner membrane, although it was unclear whether this fumarase was originally located in these fractions. No fumarase activity was detected in the intermembranous space.

Effect of lipid composition of liposomes on their sensitivity to peroxidation.

Abstract: The effect of lipid composition of liposomes on peroxidation induced by ferrous ion and ascorbate was examined. Temperature affects the sensitivity of liposomes; the peroxidation rate was increased with increase of the incubation temperature. With liposomes consisting of 1-palmitoyl-2-arachidonyl phosphatidylcholine (substrate) and a peroxidation-insensitive lipid, 1-palmitoyl-2-oleoyl phosphatidylcholine, peroxidation was dependent on the density of the substrate. No appreciable peroxidation was observed with liposomes containing less than 10 mol% of the substrate at 37 degrees C. When 1 mol substrate was mixed with 9 mol dimyristoyl phosphatidylcholine, peroxidation occurred below 10 degrees C, but not above 20 degrees C. Above 20 degrees C, the substrates should be located homogeneously on the membranes, whereas they should be clustered below 10 degrees C, since the gel-liquid crystalline phase transition temperature of matrix membrane of dimyristoylphosphatidylcholine was 17-21 degrees C. Peroxidation of liposomes consisting of 1-palmitoyl-2-arachidonyl phosphatidylcholine was also suppressed by cholesterol. These findings indicate that the lateral distribution as well as the density of the substrate on membranes affects the sensitivity of the substrate to peroxidation. It was also found that alpha-tocopherol is preferentially located in the 1-palmitoyl-2-arachidonyl phosphatidylcholine-rich regions of membranes consisting of mixed phospholipids, and efficiently suppresses peroxidation of liposomal lipids.

Isolation and characterization of a lectin from edible mushroom, Volvariella volvacea.

Abstract: A lectin was purified from edible mushroom, Volvariella volvacea by extraction with 5% cold acetic acid in the presence of 0.1% 2-mercaptoethanol, followed by ammonium sulfate fractionation, and DEAE-C-52 and CM-C-52 column chromatographies. The molecular weight was measured to be 26,000, and the lectin consisted of two non-identical subunits as demonstrated by gel filtration and polyacrylamide gel electrophoresis. The lectin does not contain half-cystine, methionine, or histidine. The LD50 of the lectin is 17.5 mg per kg body weight of mice. The lectin has a moderate inhibitory effect on the growth of tumor cells.

The primary structure of phosphoenolpyruvate carboxylase of Escherichia coli. Nucleotide sequence of the ppc gene and deduced amino acid sequence.

Abstract: The nucleotide sequence of the ppc gene, the structural gene for phosphoenolpyruvate carboxylase [EC 4.1.1.31], of Escherichia coli K-12 was determined. The gene codes for a polypeptide comprising 883 amino acid residues with a calculated molecular weight of 99,061. The amino acid sequence deduced from the nucleotide sequence was entirely consistent with the protein chemical data obtained with the purified enzyme, including the NH2- and COOH-terminal sequences and amino acid composition. The coding region is preceded by two putative ribosome binding sites, and is followed closely by a good representative of rho-independent terminator. The codon usage in the ppc gene suggests a moderate expression of the gene. The secondary structure of the enzyme was predicted from the deduced amino acid sequence.

Gangliosides of various rat tissues: distribution of ganglio-N-tetraose-containing gangliosides and tissue-characteristic composition of gangliosides

Abstract: Gangliosides were extracted from various tissues of rat (Wistar strain, male, 3 months old) and their structures were elucidated by enzymatic and chemical procedures including the analysis by negative ion fast atom bombardment mass spectrometry. All tissues analyzed contained gangliosides in various but characteristic concentrations. GD1a was detected in the various extraneural tissues (erythrocytes, buffy coat, bone marrow, testis, spleen, and liver) in amounts corresponding to more than 30% of total lipid-bound sialic acid, and surprisingly, it was the sole ganglioside found in buffy coat. The extraneural tissues were classified into several categories according to the nature of the asialo-oligosaccharides of gangliosides as follows: (1) gangliosides with ganglio-N-tetraose were exclusively present (buffy coat and erythrocytes), (2) the concentration of ganglio-N-tetraose-containing gangliosides was higher than that of lactose-containing gangliosides (testis and bone marrow), (3) ganglio-N-tetraose-containing gangliosides amounted to 25-30% of lactose-containing gangliosides (liver and spleen), (4) ganglio-N-tetraose-containing gangliosides amounted to 7-11% of lactose-containing gangliosides (lung and stomach), (5) more than 90% of gangliosides were lactose-containing gangliosides (heart, intestine, and kidney). In addition, the following gangliosides were characteristically detected in high concentration in the following tissues: GM4 in kidney. GM2 in bone marrow, fucosyl GM1 and GM1 in erythrocytes and GM3 with 2-hydroxy fatty acid, phytosphingosine and N-glycolylneuraminic acid in intestine.

Purification and Characterization of a Lectin from the Beetle, Allomyrina dichotoma

Abstract: A lectin was purified from the hemolymph of Allomyrina dichotoma larvae by affinity chromatography on acid-treated Sepharose 4B. The purified lectin showed two protein bands on polyacrylamide gel electrophoresis. These two lectin bands (allo A-I and -II) were separated by DEAE-Cellulofine column chromatography. By gel filtration on Sephadex G-100, the molecular weights of allo A-I and -II were estimated to be 65,000 and 66,500, respectively. On the other hand, by SDS-polyacrylamide gel electrophoresis after cross-linking of subunits with glutaraldehyde, they are estimated to be 38,000 and 39,000, respectively. On SDS-polyacrylamide gel electrophoresis, it was proved that both allo A-I and -II lectin consisted of two subunits, respectively. The molecular weights were 17,500 and 20,000 for allo A-I, and 19,000 and 20,000 for allo A-II. The isoelectric points of allo A-I and -II were estimated to be 6.4 and 5.9, respectively. On double immunodiffusion, allo A-I and -II gave single precipitin lines, which fused completely with each other, against the antibody to crude allo A. The hemagglutinating activity of allo A-I and -II was inhibited only by beta-linked D-galactose such as lactose and lactulose.

Direct interaction of calmodulin antagonists with Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase.

Abstract: Trypsin-treated Ca2+/calmodulin-dependent phosphodiesterase (CA2+-PDE), which had lost its sensitivity to Ca2+-calmodulin, was inhibited by various calmodulin antagonists, trifluoperazine, chlorpromazine, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) and aminoalkyl chain analogues of W-7 (A-3, A-4, A-5, I-240, A-6, A-7). These inhibitory effects were less than those on calmodulin-activated Ca2+-PDE. The ability of these compounds to inhibit trypsin-treated Ca2+-PDE correlated well with the inhibitory effect on calmodulin-activated Ca2+-PDE. W-7 inhibited trypsin-treated Ca2+-PDE in a competitive fashion with respect to cyclic GMP and the Ki value was 300 microM. The inhibition of trypsin-treated Ca2+-PDE by W-7 (300 microM) or A-7 (100 microM) was overcome by the addition of excess calmodulin. Trypsin-treated Ca2+-PDE can bind to W-7-coupled cyanogen bromide-activated Sepharose 4B in the presence of 1 mM EGTA. These results suggest that Ca2+-PDE possesses a binding site for calmodulin antagonists and that the binding site for these antagonists on this enzyme may be structurally similar to the binding site on calmodulin itself.

Modification of sialic acid carboxyl group of ganglioside.

Abstract: A simple and quantitative method for the modification of sialic acid carboxyl group in ganglioside is described. Methyl iodide was added to the ganglioside in dimethylsulfoxide. The reaction was completed quickly at room temperature, giving the methyl ester with practically no by-products. Reduction of the methyl ester was achieved by sodium borohydride. These modified gangliosides were chemically characterized. Reduced GM1 has a strong antigenicity compared with the original GM1, and it raised high titer antisera which did not crossreact with the original GM1 nor with its methyl ester. Peanut agglutinin, which binds strongly to asialo GM1 but weakly to GM1, bound to the methyl ester of GM1 and reduced GM1. Cholera toxin, which is specific for GM1, also reacted with the methyl ester of GM1 and reduced GM1 to a certain extent.

Isolation of cytochrome P-450 highly active in prostaglandin omega-hydroxylation from lung microsomes of rabbits treated with progesterone.

Abstract: Two forms of cytochrome P-450, designated as cytochrome P-450p-1 and cytochrome P-450p-2, were separated and purified to specific contents of 8.2 and 8.9 nmol/mg of protein, respectively, from lung microsomes of rabbits treated with progesterone. Cytochrome P-450p-1 and cytochrome P-450p-2 migrated as single polypeptide bands with molecular weights of 49,000 and 52,000, respectively, on SDS-polyacrylamide gel. Their CO-reduced difference spectral peaks were at 451.5 and 450 nm, respectively. Cytochrome P-450p-1 catalyzed the N-demethylation of benzphetamine, O-demethylation of p-nitroanisole, and O-deethylation of 7-ethoxycoumarin, whereas no activity was observed with cytochrome P-450p-2. On the other hand, cytochrome P-450p-2 catalyzed the omega-hydroxylation of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), and prostaglandin A1 (PGA1) with turnover rates of 9.0, 7.5, and 5.0 nmol of product/min/nmol of cytochrome P-450, respectively, as well as the omega- and (omega-1)-hydroxylation of palmitate and myristate with turnover rates of 27.7 and 16.4 nmol products/min/nmol of cytochrome P-450, respectively. This cytochrome showed a greater affinity for prostaglandins (PGs) than for fatty acids. These reactions were absolutely dependent on cytochrome P-450p-2 and NADPH-cytochrome P-450 reductase, and stimulated by addition of phosphatidylcholine and cytochrome b5. Cytochrome P-450p-2 is thought to be a new form of cytochrome P-450 induced by progesterone treatment in rabbit lung microsomes.