Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding of Ca2+ to a salivary phosphoprotein, protein C, was studied by equilibrium dialysis. In 5mM-Tris/HCl buffer, pH 7.5, protein C bound 190 nmol of Ca2+/mg of protein. The apparent dissociation constant, K, was determined to be 1.9 x 10(-4)M and the binding of Ca2+ to the protein was non-co-operative. The binding of Ca2+ to protein C apparently depends on groups which ionize above pH 5.0. Ca2+ binding decreased with increased concentration of the dialysis buffer and on addition of SrCL2, MgCl2 and MnCl2 to the dialysis buffer. Digestion of protein C with trypsin or collagenase or heating of the protein to 60 degrees or 100 degrees C had little or no effect on the Ca2+ binding. Digestion of protein C with alkaline phosphatase caused a decrease in the amount of protein-bound Ca2+. This was also found for another salivary phosphoprotein, protein A. In the absence of Ca2+ the S020,w for protein C was 1.29 S and in the presence of Ca2+ it was 1.46S. Ca2+ may cause a conformational change in the protein or an aggregation of the protein molecules. No conformational changes of protein C in the presence of Ca2+ could be detected by circular dichroism or nuclear magnetic resonance.
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PMID:The binding of calcium to a salivary phosphoprotein, protein C, and comparison with calcium binding to protein A, a related salivary phosphoprotein. 1 96

The synthesis and alpha-adrenoreceptor blocking activity of several substituted analogs of the prototype alpha-blocker N,N'-bis-(5-aminopentyl)cystamine (APC) are described. The three optical forms of the analog carrying methyl groups on the carbons alpha- to the sulfurs were synthesized and shown to be equipotent and somewhat less active than APC. The omega, omega'-bis-guanidino analog of APC was less active. Significant improvement in potency was observed only with APC analogs carrying benzyl and substituted benzyl groups on the terminal nitrogens. Linking the terminal nitrogens of APC with a p.xyledenyl group so as to give the 26-membered analog caused a sharp drop in activity. The significance of these results as regards the alpha-receptor topography is discussed.
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PMID:Molecular properties of the adrenergic alpha-receptor. I--Structural requirements for specific covalent occupancy by N,N'-bis--(5-aminopentyl)cystamine derivatives. 3 32

In connection with the elucidation of the possibility of photochemical participation of phycobiliproteins in the primary processes of photosynthesis, the ability of a mixture of phycocyanin + allophycocyanin (PC + APC) for photosensitization of redox reactions in the adsorbed state was investigated. It was shown that adsorbates of PC + APC on Sephadexes G-200 and G-25, diethylaminoethylcellulose, carboxyethylcellulose, Bacto-agar, Lifogel, polyethylene glycol, Dowex 50Wx2, and aluminum oxide are capable of sensitizing the photoreduction of methyl red by ascorbid acid. In this case the effectiveness of the sensitizing action depends on the concentration of the adsorbate, the pigment concentration on the carrier, the pH of the medium, and the nature of the solvent. It was shown that in the case of binding to a carrier, the sensitizing ability of PC + APC increases in comparison with that for pigments in the dissolved state. It is suggested that this is promoted by an increase in the concentration and a mutual approach of the reagents after adsorption, and the possible formation of complexes of some or all the participants of the reaction on the surface of the adsorbent.
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PMID:The photosensitizing action of phycobiliproteins in the adsorbed state. 3 27

The relationship between poly(adenosine diphosphate) ribosylation of nuclear proteins and functionally different forms of chromatin from mid-S-phase HeLa nuclei was investigated. The major observations emerging from this study were that unique nonhistone proteins were modified in mid-S-phase HeLa nuclei. The major acceptor for poly(adenosine diphosphate-ribose) [poly(ADP-Rib)] was an internucleosomal nonhistone protein (protein C; 125 000 molecular weight). Histones H3, H1, H2b, and H2a but not H4 were ADP-ribosylated in S-phase nuclei. Chromatin fragments preferentially released by micrococcal nuclease were enriched in nonhistone proteins, poly(ADP)-ribosylated nuclear proteins, poly(ADP-Rib) polymerase activity and nascent DNA from the DNA replicating fork. In extended forms of chromatin, contiguous to the DNA replicating fork, poly(ADP-Rib) polymerase was maximally active. However, in chromatin distal to the replicating fork (i.e., more condensed structures), nucleosomal histones and histone H1 were not significantly ADP-ribosylated, and poly(ADP-Rib) polymerase activity was depressed two- to threefold. The data suggest that a subset of nucleosomes in extended regions of chromatin is subject to extensive ADP ribosylation.
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PMID:Nuclear protein modification and chromatin substructure. 3. Relationship between poly(adenosine diphosphate) ribosylation and different functional forms of chromatin. 10 78

The partial purification and characterization of specific rat epididymal proteins (SEP) is reported. Starting from the cytosol fraction obtained from epididymal homogenates, protein C was purified 15-fold and proteins D--E were purified 19-fold. The molecular weight, determined by molecular sieving, of protein C was 22,400 while that of D--E was 37,000. These proteins stained as glycoproteins with periodic acid--Schiff reagent. The isoelectric point of protein D was 5.13 while that of protein E was 4.95. Protein C separated into 3 bands during isoelectric focussing. The major component focussed at 5.56 and the two minor components at pH 5.38 And 5.79. Using a specific antiserum we could confirm the organ specificity of SEP and their androgen-dependence.
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PMID:Isolation and characterization of specific rat epididymal proteins. 10 28

The binding of Ca2+ to a previously described phosphoprotein from human parotid saliva, protein A [Bennick (1975) Biochem J. 145, 557-567] was studied by means of equilibrium dialysis. In 5 mM-Tris/HC1 buffer, pH7.5, protein A bound 664nmol of Ca/mg of protein. Km was determined to be 181 muM and the binding of Ca2+ to the protein was non-co-operative. The binding of Ca2+ apparently occurs to side-chain carboxyl groups in the protein, but protein phosphate is of minor if any importance in calcium binding. Hydrolysis of protein A by trypsin and collagenase or heating of the protein at 60 degrees or 100 degrees C did not affect Ca2+ binding. The Ca2+ binding decreases with increased concentration of the dialysis buffer and on the addition of SrCl2, or MgCl2 or MnCl2 to the dialysis buffer. Protein A does not aggregate in the presence of Ca2+, since the s20,w was identical when determined in the presence (1.30S) and absence (1.35S) of CaCl2. By use of a specific antiserum to protein A it was found that protein C [Bennick & Connell (1971) Biochem. J. 123, 455-464] and perhaps minor related components cross-reacted with protein A. No other salivary proteins showed immunological similarity. Proteins A and C were also present in submandibular saliva. The possible functions of protein A are discussed.
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PMID:The binding of calcium to a salivary phosphoprotein, protein A, common to human parotid and submandibular secretions. 18 Sep 80

The proteins which have been left tightly bound to the tissue culture substrate after ethylenebis (oxyethyl-enenitrilo) tetraacetic acid (EGTA)-mediated removal of normal, virus-transformed, and revertant mouse cells and which have been implicated in the substrate adhesion process have been analyzed by slab sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Three size classes of hyaluronate proteoglycans were resolved in the 5% well gel; approximately half of the protein in the substrate-attached material coelectrophoresed with these polysaccharides-so-called glycosaminoglycan-associated protein(GAP). A portion of the GAP was shown to be highly heterogeneous and displaced from the polysaccharide by preincubation with calf histone before electrophoresis. The relative proportions of the proteoglycans varied in material deposited during a variety of cellular attachment and growth conditions. The remainder of the cellular protein in substrate-attached material was resolved as several major and distinct protein bands in 8 or 20% separating gels (a limited number of distinct serum proteins have also been identified as substrate bound). Protein C0 (molecular weight 220 000) was a prominent component in the material from a variety of normal and virus-transformed cells and resembled the so-called LETS or CSP glycoprotein in several respects; protein Ca was myosin-like in several respects; protein C2 was shown to be actin; and protein C1 (molecular weight 56 000) does not appear to be tubulin. Histones were also present in most preparations of substrate-attached material, particularly at high levels in transformed cell meterial, and may result from EGTA-mediated leakiness of the cell and subsequent binding to the negatively charged polysaccharide. These substrate-attached proteins were (a) prominent in substrate-attached material from many cell types in characteristic relative proportions, (b) deposited by EGTA-subcultured cells during the first hour of attachment to fresh substrate, (c) deposited by cells growing on plastic or glass substrates (three additional) components were also prominent in glass-attached material), and (d) deposited during long-term growth on or initial attachment to substrates coated wit 3T3 substrate-attached material. Pulse-chase analyses with radioactive leucine indicated that these proteins exhibit different turn-over behaviors. These results are discussed with regard to the possible involvement of these substrate-attached proteins in the substrate adhesion process, with particular interest in the interaction of cytoskeletal microfilaments with other surface membrane components and with regard to alteration of substrate adhesion by virus transformation.
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PMID:Electrophoretic analysis of substrate-attached proteins from normal and virus-transformed cells. 18 10

The nonhistone chromatin protein, C-14, was extracted from chromatin of Novikoff hepatoma ascites cells and isolated in high purity as shown by its migration as a single dense spot on two-dimensional polyacrylamide gels. Its mobility on sodium dodecyl sulfate gels is consistent with a molecular weight of approximately 70 000. The amino acid composition shows that protein C-14 has an acidic:basic amino acid ratio of 1.8. Its amino terminal amino acid is lysine. Protein C-14 stimulated the incorporation of [3H]UMP into RNA by approximately 30% when added to naked DNA and homologous RNA polymerase I. A 30% stimulation of [3H]UMP incorporation into RNA was also found when protein C-14 was added to an E. coli RNA polymerase system containing either E. coli or Novikoff hepatoma DNA.
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PMID:Isolation and characterization of nonhistone chromosomal protein C-14 which stimulates RNA synthesis. 19 58

Synaptosomal proteins isolated from rat cerebral cortex were phosphorylated endogeneously in the presence of [gamma-32P]ATP. The phosphorylated proteins were found to be membrane bound by differential and density gradient centrifugation. In contrast to the phosphorylation of all synaptosomal proteins, phosphorylation of one protein (C), 41 000--43 000 daltons, was inhibited by Mg2+ and stimulated by Ca2+. In addition, the ionophores X537A and A23187, as well as papaverine, selectively enhanced phosphorylation of protein C without affecting phosphorylation of the outer proteins. Cyclic AMP did not influence the phosphorylation of protein C but markedly affected the phosphorylation of other synaptosomal proteins. It appears that the phosphorylation of protein C is stimulated by agents which trigger the release of neurotransmitters (Ca2+, X537A, A23187 and papaverine), and is inhibited by Mg2+, which inhibits release. It is proposed that the phosphorylation of protein C is related to membranal events underlying the release of neurotransmitters.
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PMID:Influence of calcium on phosphorylation of a synaptosomal protein. 21 Aug 36

The amino acid sequence of the light chain of bovine protein C was determined by sequenator analysis of the carboxymethylated light chain and fragments obtained by cyanogen bromide treatment, tryptic digestion after blocking of lysine residues, and cleavage with 2-(2-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine (BNPS-skatole). The sequence was (in the standard one-letter code) A-N-S-F-L-X-X-L-R-P-G-N-V-X-R-X-C-S-X-X-V-C-X-F-X-X-A-R-X-I-F-Q-N-T-X-D-T-M-A-F-W-S-K-Y-S-D-G-D-Q-C-E-D-R-P-S-G-S-P-C-D-L-P-C-C-G-R-G-K-C-I-H-G-L-G-G-F-R-C-D-C-A-E-G-W-E-G-R-F-C-L-H-E-V-R-F-S-N-C-S-A-E-B-G-G-C-A-H-Y-C-M-E-E-E-G-R-R-H-C-S-C-A-P-G-Y-R-L-E-D-D-H-Q-L-C-V-S-K-V-T-F-P-C-G-R-L-G-K-R-M-E-K-K-R-K-T-L. The first eleven glutamic acid residues were carboxylated to gamma-carboxyglutamic acid (X). The NH2-terminal, vitamin K-dependent part showed an extensive homology to both prothrombin and factor X, whereas the rest of the chain showed a strong homology to factor X but little similarity to prothrombin.
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PMID:Bovine protein C: amino acid sequence of the light chain. 28 10


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