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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Spontaneous deamidation of a protein antibiotic, neocarzinostatin, at weakly acidic pH. Conversion to a homologous inactive preneocarzinostatin due to change of asparagine 83 to aspartic acid 83 accompanied by conformational and biological alterations. 1 34

The M4 isozyme of lactate dehydrogenase was purified to homogeneity from normal rat liver and from two Morris hepatomas (7777 and 7793). Amino-terminal analyses with fluorodinitrobenzene failed to detect the presence of free amino-terminal residues in each enzyme studied. Each enzyme contained between 3.7 and 4.1 moles of protein-bound acetyl groups per mole of enzyme. The amino-terminal peptide, characterized as N-acetylalanylalanine, was isolated from Pronase digests of each isozyme preparation, and quantitative recovery experiments indicated that all acetyl residues were bound at the amino termini. Carboxylterminal analyses demonstrated phenylalanine to be the carboxyl-terminal residue in each enzyme studied. These data indicate no differences in either amino- or carboxyl-terminal regions of the hepatoma M4 isozymes compared to normal liver M4 isozyme.
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PMID:Amino- and carboxyl-terminal analyses of hepatoma lactate dehydrogenase isozymes. 16 83

Intracellular perfusion of giant axons from Loligo forbesi with a crude protein extract of Pronase dissolved in a KF solution suppresses the process of fast inactivation of the Na conductance (the h-process in the Hodgkin-Huxley terminology). 2. The results with protease inhibitors indicate that the most substrate specific endopeptidase present in pronase, alkaline proteinase b, destroys the h-process. 3. After destruction of the inactivation the conductance rise upon depolarization followed cube law kinetics. Values of the time constant taum before and after destruction of the h-process were very similar. 4. After destruction of the inactivation process the following properties were tested: cation selectivity, instantaneous conductance and internal receptor sites for tetrodotoxin (TTX) and tetraethylammonium (TEA). No detectable changes in selectivity or instantaneous conductance were observed. No internal receptors for TTX affecting the Na conductance were found but a TEA receptor is exposed by the protein hydrolysis. 5. TEA derivatives (triethylammonium, TEA-, with an aliphatic chain, Cn) induce a partial block of the steady-state sodium current and induce a time-dependent blockage of the conductance. 6. The first effect of TEA-Cn could be described in terms of a unimolecular reaction with the following equilibrium constants: 50, 2-5, 1-0, 0-4 and 0-025 mM for TEA-C2, TEA-C4, TEA-C5, TEA-C7 and TEA-C9 respectively. 7. From the dependence of the equilibrium dissociation constant on the length of the alkyl chain we estimated the free-energy change in 560 cal/mole of CH2. The gain in free energy per CH2 group transferred from aqueous medium to the interior of a non-polar medium is 1000 cal. 8. Although with the data at hand it is impossible to propose the amino-acid sequence of the site cleaved by alkaline proteinase b, we propose that an important functional component is arginine (or lysine).
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PMID:Destruction of the sodium conductance inactivation by a specific protease in perfused nerve fibres from Loligo. 99 46

Biochemical and immunological properties of biosynthetically radiolabeled phosphatidylcholine-(PC-) binding proteins were investigated. The PC-binding proteins were extracted from the detergent lysate of biosynthetically radiolabeled P388D1 cells by affinity chromatography on PC-Sepharose and filtered through a Sephadex G-100 gel column in the presence of 6 M urea. Isoelectric focusing of the gel-filtered materials in the presence of 6 M urea revealed the presence of a major protein component of pIe of 5.8 and minor heterogeneous cellular proteins. The yield of the electrofocused PC-binding proteins based on protein determination by Lowry's method ranged from 0.7 to 4 mg per 10(9) cells. The purified PC-binding proteins appeared to be tightly associated with Triton X-100 and phospholipids in the weight ratio of 0.57 and 0.05 g/g of proteins, respectively. The majority of lipids that could be extracted from the PC-binding proteins by chloroform/methanol (2:1 v/v) are free fatty acids, whereas lipids extracted from Pronase-treated PC-binding proteins contained phosphatidylethanolamine. By amino acid analysis, the purified PC-binding proteins were found to consist of a minimum of 417 amino acid residues, suggesting a minimum molecular weight of about 38 000 for this protein. Results of radiolabeling experiments with [3H]glucosamine and amino acid analysis both showed the presence of a mole of glucosamine per a mole of the PC-binding proteins, suggesting their glycoprotein nature. About 40% of the purified PC-binding proteins coprecipitated with monoclonal anti-Fc gamma 2bR antibody (2.4G2) in detergent-containing buffer, whereas only 6% of the isolated IgG binding proteins reacted with this antibody.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biochemical properties of phosphatidylcholine-binding proteins that share common antigenic determinants with Fc gamma 2b receptor. 241 20

Phosphorylation of histone H1 occurs when spermatozoa of the sea urchin Strongylocentrotus purpuratus are treated with the macromolecular fraction of solubilized egg jelly. Phosphorylation is on serine residues in the N-terminal fragment of H1 bisected with N-bromosuccinimide. Phosphorylation is maximal by 4-8 min and dependent on Ca2+, but independent of Na+ or increased intracellular pH. Phosphorylation of H1 can be dissociated from the induction of the acrosome reaction. Only a fraction of the H1 molecules become phosphorylated upon treatment of sperm with egg jelly. The amount of phosphate per mole of H1 increases from 0.15 moles before jelly treatment to 0.46 moles after maximal phosphorylation. Phosphorylation of H1 occurs in a cAMP-dependent manner as indicated by the ability of the phosphodiesterase inhibitors IBMX and SQ20009 to induce H1 phosphorylation. This phosphorylation reaction can be blocked by digesting the sperm surface with Pronase, or preincubation of sperm in wheat germ agglutinin, showing that a ligand in egg jelly must interact with a sperm surface receptor to activate the kinase phosphorylating H1.
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PMID:Phosphorylation of sperm histone H1 is induced by the egg jelly layer in the sea urchin Strongylocentrotus purpuratus. 242 45

The complete carbohydrate structure of the asparagine-linked oligosaccharides of rat plasma thiostatin was elucidated through chemical and enzymatic methods including gas chromatography-mass spectrometry (GC-MS) and lectin affinity chromatography. Pronase digestion of thiostatin yielded a major glycopeptide fraction with asparagine the most abundant amino acid present. Based on one mole of aspartic acid, the following molar ratios obtained for the four major amino acids: aspartic acid (1.0), threonine (0.53), glycine (0.48) and serine (0.30). Neutral sugar analysis yielded a 3:2 molar ratio for mannose to galactose based on an assigned value to mannose of 3. On this basis, the fraction also contained 3 residues of sialic acid and, on average, 0 to 1 residue of fucose. GC-MS of partially methylated alditol acetates from the glycopeptide fraction identified the presence of biantennary and triantennary structure. Analyses of the neutral sugar and amino-acid composition, together with methylation data, support a biantennary N-linked structure for this major glycopeptide fraction and a triantennary N-linked structure as a lesser component. Sequencing of the desialyated 14C-labelled glycopeptide fraction by sequential exoglycosidase digestion and lectin affinity chromatography uncovered the following saccharide order: terminal galactose, N-acetylglucosamine and pentasaccharide inner core. This sequence is consistent with the N-linked glycan structures demonstrated by methylation and compositional analyses.
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PMID:The carbohydrate structure of the asparagine-linked oligosaccharides of rat plasma thiostatin. 794 64