Showing papers by "Hiroshi Maeda published in 1977"
TL;DR: The amide content of preneocarzinostatin (PRE) was determined by analysing asparagine and glutamine in the Pronase-aminopeptidase M digests of tetra-S-carboxymethyl-NCS and carboxyl-modified NCS (modified with a water-soluble carbodiimide and [14C]glycine methyl ester) as discussed by the authors.
Abstract: The amide content of neocarzinostatin (NCS), an antitumor protein, has been determined by analysing asparagine and glutamine in the Pronase-aminopeptidase M digests of tetra-S-carboxymethyl-NCS and carboxyl-modified NCS (modified with a water-soluble carbodiimide and [14C]glycine methyl ester). Preneocarzinostatin (PRE) was separated and purified from a crude NCS preparation by CM-cellulose column chromatography. PRE was found to contain one mole less asparagine than NCS, and asparagine was deamidated to aspartic acid in PRE. A time-dependent conversion of NCS to PRE at pH 3.2 at 4 degrees or in 0.1 M acetic acid at 26 degrees was studied in two ways; first, by quantitative determination of NCS and PRE by CM-cellulose column chromatography and second, by following the release of free NH3 during dialysis in an air-tight container. Within experimental error, PRE was indistinguishable from NCS in amino acid content after acid hydrolysis, as well as in apparent molecular weight as determined by SDS-disc gel electrophoresis (10% acrylamide), and N- and C-terminal amino acid residues. Both NCS and PRE shared a common antigenicity as determined by Ouchterlony's agar diffusion method. Only a slight difference between the two in electrophoresis on a cellulose acetate membrane and on a peptide map of the tryptic digest was demonstrated. PRE, however, was completely devoid of biological activity. In addition to the chromatographic difference, a conformational difference was observed by CD spectroscopy, namely, an apparently looser structure of PRE was indicated by the shallowness of the trough in the 240-265 nm region. This interpretation was supported by the finding that digestions by Pronase were more extensive with PRE than with NCS. These results indicate an important role of the single asparagine residue (Asn 83) of NCS in the biological activity, which is evidently governed by the conformation.
26 citations
TL;DR: Temperature-jump experiments were performed with di, tetra-, and hexasaccharides derived from type III pneumococcal polysaccharide using a homogeneous corresponding antibody IgG 45-394 and a mechanism is proposed which consists of a fast formation of a labile oligosaccharide-antibody precomplex followed by a slow isomerization step which is induced by the oligosACcharide ligands but which is chain-length independent.
Abstract: Temperature-jump experiments were performed with di-, tetra-, and hexasaccharides derived from type III pneumococcal polysaccharide using a homogeneous corresponding antibody IgG 45-394. A decrease in stability of the oligosaccharide-antibody complexes with decreasing chain length was observed and entirely reflected in the decrease of the association rate constants which were 1.7 X 10(4) M-1 s-1 for the di-, 3.7 X 10(5) M-1 s-1 for the tetra-, and 1.1 X 10(6) M-1 s-1 for the hexasaccharide at 23 degrees C. The dissociation rate constants for all oligomers were about 12 s-1. This marked chain-length dependence of the association rate constants as well as their low values are unexpected for a single binding step. A mechanism is proposed which consists of a fast formation of a labile oligosaccharide-antibody precomplex followed by a slow isomerization step which is induced by the oligosaccharide ligands but which is chain-length independent.
19 citations
TL;DR: Evidence is presented for the absorption of NCS into bladder tissue from the lumen of the bladder, as shown by the appearance of a low-molecular-weight fragment and by the absence of such an increase in the presence of inhibitors of proteolysis.
Abstract: Some aspects of the absorption, distribution, and excretion of neocarzinostatin (NCS), a proteinous antitumor antibiotic, were studied in rabbits. NCS was given intravenously (i.v.) via the auricular vein, or [14C]NCS was instilled directly into the cavity of the bladder by tubing. In both groups, ureterostomy was performed, so that the drug excreted in the urine did not pass through the bladder. The results showed extremely rapid renal clearance; namely, two-thirds of the total recovered was excreted in the first 5 min. It was also shown that drug infused into the bladder cavity could be recovered in urine from the ureterostomized ureter. Also, the level of biological activity of NCS in bladder tissues after i.v. administration is significantly lower when ureterostomy is performed. Thus, evidence is presented for the absorption of NCS into bladder tissue from the lumen of the bladder. The high levels of NCS in bladder tissue are due to this effect as well as to accumulation via the iliac artery. These data should encourage further trials of NCS in bladder cancer. A study of urine containing NCS derived from i.v. administration showed an increase in antibacterial activity upon incubation, followed by a decrease. These effects are probably due to proteolysis, as shown by the appearance of a low-molecular-weight fragment and by the absence of such an increase in the presence of inhibitors of proteolysis.
17 citations
Patent•
18 Oct 1977
TL;DR: An electrical contact material consisting essentially of silver and a small amount of zinc oxide, tellurium oxide, and optionally indium oxide and tin oxide, these oxides being uniformly dispersed in the silver matrix.
Abstract: An electrical contact material consisting essentially of silver and a small amount of zinc oxide, tellurium oxide, and optionally indium oxide and tin oxide, these oxides being uniformly dispersed in the silver matrix.
13 citations