Showing papers on "Gel electrophoresis published in 1982"

Alzheimer's disease: insolubility of partially purified paired helical filaments in sodium dodecyl sulfate and urea

Abstract: A method is described for the partial purification of the paired helical filaments that accumulate progressively in human neurons in Alzheimer's disease (senile dementia). Paired helical filaments have unusual solubility characteristics, including insolubility in sodium dodecyl sulfate, urea, reducing agent, and guanidine, which prevent analysis of their molecular composition by gel electrophoresis. The paired helical filaments appear to contain covalent bonds other than disulfide, which cross-link individual filaments into a rigid intracellular polymer. Thus, paired helical filaments appear to represent an example in neurons of an insoluble cross-linked protein. Covalently cross-linked protein polymers occur in lens senile cataracts and in terminally differentiated skin keratinocytes, suggesting that there may be a common mechanism for remodeling some structural proteins during cell aging.

Human melanoma-associated antigen p97 is structurally and functionally related to transferrin

Abstract: p97 is a 97,000-molecular weight (MW) cell-surface glyco-protein, which is present in most human melanomas but in only trace amounts in normal tissues1–4. We describe here the purification of p97 by affinity chromatography with monoclonal antibody, followed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and determination of the N-terminal amino acid sequence using a new, highly sensitive protein sequencer5. The sequence was found to be homologous to the N-terminal sequences of transferrin and lactotransferrin. This structural homology was confirmed by the observation that antiserum to denatured p97 cross-reacted with denatured transferrin and lactotransferrin. We have also demonstrated that p97 is functionally related to transferrin and lactotransferrin in that it binds iron. This is one of the first reports of the amino acid sequence of a human tumour-associated cell-surface antigen and one of the few cases in which insight has been obtained into its function.

Purification of zymogen to plasminogen activator from human glioblastoma cells by affinity chromatography with monoclonal antibody.

Abstract: Incorporation of the serine protease active site reagent diisopropyl fluorophosphate (DFP) into a plasminogen activator with an Mr of approximately 52000 released from cultured human glioblastoma cells was strongly enhanced by incubation with plasmin. This observation led to the isolation of an inactive form of the enzyme from serum-free conditioned culture fluid by affinity chromatography on a column of a Sepharose-bound monoclonal antibody raised against urokinase. An 831-fold purification was obtained with a yield of 41%. The purified molecule was homogeneous as evaluated by polyacrylamide gel electrophoresis with sodium dodecyl sulfate (NaDodSO4), having one stainable band under nonreducing as well as reducing conditions with an Mr of approximately 52000. It was unable to activate plasminogen, but catalytic amounts of plasmin converted it into active enzyme. After NaDodSO4-polyacrylamide gel electrophoresis, the active enzyme showed one band under nonreducing conditions, but after reduction, two bands with Mr values of approximately 20000 and 32000 were observed. The active enzyme incorporated [3H]DFP into the approximately Mr 32000 band, while no incorporation was observed into the inactive form. These findings show that the Mr 52000 human plasminogen activator exists in a proenzyme form consisting of a single polypeptide chain that by proteolysis between half-cystine residues is converted into the active enzyme consisting of two chains with molecular weights of approximately 20000 and 32000, the active site being on the latter chain. The results are consistent with the active form of the enzyme being identical with the higher molecular weight form of urokinase, and together with recent observations that a murine plasminogen activator is released from sarcoma virus transformed cells as an inactive proenzyme, they suggest that zymogens to plasminogen activators are of more general occurrence.

Characterization of the platelet membrane glycoprotein abnormalities in Bernard-Soulier syndrome and comparison with normal by surface-labeling techniques and high-resolution two-dimensional gel electrophoresis.

Abstract: The platelets from three patients with Bernard-Soulier syndrome have been analyzed by surface-labeling coupled with two-dimensional gel electrophoresis and compared with normals. As well as the previously described absence or deficiency in glycoprotein (GP) Ib(alpha) it could be shown that GP Ib beta and an additional low molecular weight glycoprotein GP17 were not detectable using carbohydrate-labeling methods or deficient to the same extent as the GPIb alpha subunit. In addition, the thrombin cleavable glycoprotein could not be detected using carbohydrate-labeling methods in two patients and was deficient in a third. This finding was confirmed in a fourth patient by one-dimensional gel electrophoresis. Thus, the changes in the membrane of Bernard-Soulier platelets are more complex than previously thought.

Gel electrophoresis of nucleic acids: a practical approach

Abstract: Gel electrophoresis of RNA, D.Grierson gel electrophoresis of DNA, P.G.Sealey pulsed field gel electrophoresis, R.Anand the electrophoresis of synthetic oligonucleotides, J.W.Efcavitch two-dimensional gel electrophoresis of nucleic acids, R de Wachter et al gel retardation of nucletic acid-protein interactions, M.M.Garner the analysis of sequence-specific DNA-binding proteins in cell extracts, G.H.Goodwin electrophoresis of nucleosomes, R.H.Nicholas gel electrophoresis of ribonuceotides, A.E.Dahlberg and P.J.Grabowski.

Purification and Characterization of a Ca2+- and Calmodulin-Dependent Protein Kinase from Rat Brain

Abstract: A Ca2+- and calmodulin-dependent protein kinase was purified from rat brain cytosol fraction to apparent homogeneity at approximately 800-fold and with a 5% yield. The purified enzyme had a molecular weight of 640,000 as determined by gel filtration analysis on Sephacryl S-300 and a sedimentation coefficient of 15.3 S by sucrose density gradient centrifugation, and resulted in a single protein band of MW 49,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results suggest that the native enzyme has a large molecular weight and consists of 11 to 14 identical subunits. The purified enzyme exhibited Km values of 109 and 30 microM for ATP and chicken gizzard myosin light chain, respectively, and Ka values of 12 nM and 1.9 microM for brain calmodulin and Ca2+, respectively. In addition to myosin light chain, myelin basic protein, casein, arginine-rich histone, microtubule protein, and synaptosomal proteins were phosphorylated by the enzyme in a CA2+- and calmodulin-dependent manner. The purified enzyme was phosphorylated without the addition of the catalytic subunits of cyclic AMP-dependent protein kinase. Our findings indicate that there is a multifunctional Ca2+- and calmodulin-dependent protein kinase in the brain and that this enzyme may regulate the reactions of various endogenous proteins.

Purification and properties of inducible penicillin beta-lactamase isolated from Pseudomonas maltophilia.

Abstract: Two types of beta-lactamase were found in the cell-free extract from Pseudomonas maltophilia GN12873. One was an inducible penicillin beta-lactamase, and the other was an inducible cephalosporin beta-lactamase. The purified penicillin beta-lactamase gave a single protein band on polyacrylamide gel electrophoresis. The isoelectric point was 6.9, and the approximate molecular weight was 118,000 by gel filtration and 26,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that this enzyme consisted of four subunits. For the hydrolysis of penicillin G, the optimal pH was 8.0 and the optimal temperature was 35 degrees C. The enzyme activity was inhibited by cephamycin derivatives, carpetimycins A and B, iodine, and HgCl2, but not by clavulanic acid. Furthermore, beta-lactamase activity was almost completely inhibited by EDTA but was recovered by the addition of zinc ion. The enzyme showed a unique substrate profile, hydrolyzing N-formimidoyl thienamycin at a significant rate.

Variable major proteins of Borrellia hermsii.

Abstract: Borrelia hermsii, a relapsing fever agent, manifests antigenic variation in vivo and in vitro. We studied three mouse-passaged serotypes of strain HS1 (7, 14, and 21) and a HS1 derivative obtained after multiple in vitro passages (C serotype). All four serotypes had two major proteins in whole cell lysates fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. One major protein species (pII) had the same apparent subunit molecular weight (or approximately 3.9 X 10(4) in all the serotypes. In contrast, the other abundant protein in lysates, pI, had a different apparent molecular weight in each serotype. In one gel the molecular weights of pIc, pI7, pI14, and pI21 were 1.9, 4.2, 4.1, and 4.0 X 10(4), respectively. Serotype-specific mouse antisera bound to both hemologous and heterologous pIIs, to homologous pI, but not to heterologous pI in Western blots. Hybridomas were raised from spleens of mice infected with B. hermsii. Monoclonal antibodies were identified by immunofluorescence assays using whole organisms. Monoclonal antibodies specific for serotype 7 (H1826) or for serotype 21 (H3326) bound only to pI7 or pI21, respectively, in Western blots. The surface location of the pI was suggested not only by the immunofluorescence studies but also by the labeling of pI7 and pI21 when whole cells of serotypes 7 and 21 were incubated with 125I in the presence of Iodogen. Under the same circumstances, pII was relatively poorly labeled. These studies have identified the variable pI proteins of B. hermsii as serotype-specific antigens. A change from one pI to another may be the basis of antigenic variation of Borrelia species during relapsing fever.

Characteristics of the isolated purine nucleotide binding protein from brown fat mitochondria.

Abstract: The isolation of the purine nucleotide binding protein (NbP), the putative uncoupling protein, from hamster brown adipose tissue mitochondria and some of its functional characteristics are described. (1) Among various detergents tested, Triton is the most suitable; the total GDP binding capacity can be recovered after solubilization by Triton and is rather stable in this extract. (2) For separation of NbP from the ADP/ATP carrier, differences in the solubilizing conditions and the stability at room temperature between both proteins are exploited. The preparation is substantially free of ADP/ATP carrier. (3) The purified NbP has a binding capacity for 16 mumol of GDP/g of protein, corresponding to a 16-fold purification from mitochondria. (4) In sodium dodecyl sulfate-polyacrylamide gel electrophoresis in single band of Mr 32 000 is found. A dimer structure is suggested from chemical cross-linking, from the binding capacity for GDP, and from the previously reported centrifugation equilibrium. (5) The isolated NbP preparation consists of Triton-protein-phospholipid mixed micelles with a Stokes radius of 60.5 A as determined by gel filtration. The Triton binding is 1.9 g/g of protein, and the phospholipid binding is 0.2 g/g of protein. (6). The amino acid composition has a polarity index of 43.5%. The N-terminal peptide has the sequence Val-Asp-Pro-Thr-Thr-Ser-Glu-Val. (7) The affinity of NbP for different purine nucleotides decreases in the order GTP greater than GDP greater than ATP greater than ITP greater than ADP greater than IDP. The affinity for the monophosphates is 100 time lower. (8) Photooxidation and the lysine reagent 2,4,6-trinitrobenzenesulfonic acid decrease the binding capacity without influencing the affinity of the unaffected sites. GDP protects against photooxidation.

Monosaccharide transporter of the human erythrocyte. Characterization of an improved preparation.

Abstract: The human erythrocyte monosaccharide transporter has been purified through the use of the dialyzable detergent octyl glucoside. It was found that the transporter denatures in the detergent and that the rate of this process could be reduced by increasing the ratio of phospholipid to detergent. The transporter was obtained in higher yield and with a higher specific activity for cytochalasin B binding than has been previously reported. Scatchard plot analysis of cytochalasin B binding to the reconstituted preparations gave a dissociation constant of 1.5 X 10(-7) M, and there were found to be 15.3 nmol of sites/mg of protein. On the basis of a value of 46 000 for the molecular weight of the polypeptide, this specific activity corresponds to 0.70 site/polypeptide chain; and there are reasons to believe that the value of the stoichiometry may be one site per functional transporter polypeptide. The complete amino acid composition and the N- and C-terminal residues of the transporter have been determined. Both the intact transporter and transporter that had been partially depleted of carbohydrate by treatment with endo-beta-galactosidase were found to migrate anomalously upon sodium dodecyl sulfate--polyacrylamide gel electrophoresis, relative to the behavior of standard proteins.

Outer membrane proteins of Brucella abortus: isolation and characterization.

Abstract: Outer membrane proteins were derived from one rough and four smooth strains of Brucella abortus by sequential extraction of physically disrupted cells with N-lauroylsarcosinate and dipolar ionic detergent. Extraction of outer membrane proteins was ineffective, however, without predigestion with lysozyme. Three groups of proteins were present and could be separated in their native state by sequential anion-exchange chromatography and gel filtration. Membrane proteins contained substantial quantities of tightly adherent lipopolysaccharide which could be reduced but not eliminated by extraction of cells with trichloroacetic acid before disruption. Group 2 proteins, apparently trimers in their native state, gave rise to 43,000- and 41,000-molecular-weight bands after complete denaturation in sodium dodecyl sulfate. They were antigenically identical among all the strains, showed close resemblance in amino acid composition to each other and a general similarity to OmpF of Escherichia coli, and are proposed to be the porins of B. abortus. Group 3 proteins occurred as 30,000-molecular-weight bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, although additional bands were frequently observed in this region. In none of the strains did group 3 proteins manifest heat-modifiable characteristics. Proteins of different strains bore a high degree of similarity to each other in amino acid composition, except in methionine, isoleucine, tyrosine, and histidine. Differences occurred consistently in amino acid composition between group 2 and 3 proteins, and some of these correspond to differences between OmpF and OmpA. Group 2 and 3 proteins were antigenically distinct from each other, but the principal group 3 antigens were shared among all the strains. Despite the lack of heat modifiability, perhaps influenced by adherent lipopolysaccharide, group 3 proteins are proposed as counterparts to OmpA. Most of the group 1 proteins, minor components, were physically associated with those of group 3 unless in sodium dodecyl sulfate. Group 1 proteins produced a major band at 94,000 and exhibited heat modifiability. No evidence was found of a low-molecular-weight lipoprotein in the outer membrane of B. abortus, but this is not taken to exclude its occurrence.

Immunocytochemical localization of the lens main intrinsic polypeptide (MIP26) in communicating junctions.

Abstract: Plasma membranes of vertebrate lens fiber cells contain a major intrinsic polypeptide with an apparent molecular weight of 26,000 (MIP26). These plasma membranes are extremely rich in communicating junctions, and it has been suggested that MIP26 is a component of them. MIP26 was purified from cow lenses using preparative SDS gel electrophoresis followed by hydroxylapatite column chromatography. From gel electrophoresis patterns and aggregational properties it was concluded that the MIP26 preparation was homogeneous. The purified MIP26 was used to produce monospecific antibodies in rabbits as assessed by double immunodiffusion and crossed immunoelectrophoresis of purified MIP26 and solubilized lens plasma membranes against the antiserum. Indirect immunocytochemical studies were performed on open and closed lens plasma membrane vesicles by incubation in anti-MIP antiserum followed by ferritin-conjugated goat antirabbit IgG. The conjugate bound unequivocally to lens communicating junctions, indicating that MIP26 is a component of these structures.

Phosphorylation of synthetic peptides by a tyrosine protein kinase from the particulate fraction of a lymphoma cell line

Abstract: The particulate fraction from a lymphoma cell line, LSTRA, was found to contain an apparent high level of tyrosine protein kinase activity. When this fraction was incubated with [gamma-32P]ATP in the presence of 10 mM MnCl2, hydrolyzed, and assayed, 70--80% of the radioactivity recovered in phosphoamino acids was in phosphotyrosine. Gel electrophoresis of the proteins showed that a large portion of the 32P was in a single protein with a molecular weight of approximately 58,000. The phosphorylated residue in this protein was identified as phosphotyrosine. Detergent extracts of the particulate fraction from LSTRA cells contained both the Mr 58,000 protein and the enzyme responsible for its phosphorylation. These extracts were found to catalyze the phosphorylation of the tyrosine residue in the synthetic peptide, Ile-Glu-Asp-Asn-Glu-Tyr-Thr-Ala-Arg-Gln-Gly, corresponding to the sequence around the tyrosine that is phosphorylated in pp60src; the Km for the peptide in this reaction was 5 mM. High-performance liquid chromatography was used to assay for this phosphorylation. A second peptide was synthesized that contained two additional arginine residues whose presence permitted the phosphorylation of the peptide to be measured by a simple assay using phosphocellulose paper. The Km for this peptide was 3--4 mM, indicating that the presence of the additional arginine residues did not alter the apparent affinity of the kinase for the peptide.

Isolation and characterization of mucin-like glycoprotein in human milk fat globule membrane.

Abstract: Milk fat globule membrane (MFGM) enclosing fat droplets in human milk was found to contain a high molecular weight glycoprotein which did not migrate in 10% acrylamide gel on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This glycoprotein (termed PAS-0) was isolated by Sepharose CL-4B chromatography. Isolated PAS-0 gave one band on SDS-PAGE using 5% acrylamide gel (acrylamide : bisacrylamide = 4 : 1, w/w) and gave one peak on analytical ultracentrifugation, indicating its homogeneity. PAS-0 was rich in serine, threonine, proline, glycine, and alanine. In contrast, contents of sulfur-containing amino acids were very low. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid were detected as constituent sugars of PAS-0 and the total carbohydrate content was about 50%. Alkali-borohydride treatment suggested that the carbohydrate moiety was linked to the polypeptide core with O-glycosidic bond(s). There results suggested that PAS-0 was a mucin-like glycoprotein. PAS-0 was shown to be resistant to pepsin, trypsin and chymotrypsin digestion, but susceptible to Pronase and Subtilisin BPN'. Extraction of intact milk fat globules (cream) with MgCl2 and guanidine hydrochloride solutions suggested that PAS-0 was an intrinsic component of MFGM. Digestion of cream with Subtilisin BPN' demonstrated that PAS-0 was located on the external surface of fat globules and was accessible to molecules outside the globules. By agglutination-inhibition tests using eight lectins, PAS-0 was suggested to act as surface receptors for Ricinus communis agglutinin, wheat germ agglutinin and peanut agglutinin.

Identification of the cap binding protein of influenza virus

Abstract: The presence of a cap binding protein in influenza virus PR8 has recently been demonstrated by photoaffinity labelling with the cap-analogue (gamma [3 2P]-[4-(benzoylphenyl)methylamido]-7-methylguanosine 5'-triphosphate). This paper describes the identification of the labelled protein using two-dimensional gel electrophoresis. The protein is shown to be PB2, the smaller of the two basic P proteins in the polymerase complex.