Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Electron spin echo envelope modulation (ESEEM) experiments have been used to investigate the Mn(2+)-binding site in a series of lectins including concanavalin A, pea lectin (Pisum sativum), isolectin A from lentil (Lens culinaris), soybean agglutinin (Glycine max), Erythrina indica lectin, and Lotus tetragonolobus isoelectin A. Together with model studies, the results provide direct evidence for a single nitrogen atom of a conserved residue bonded directly to Mn2+ in all of them. ESEEM measurements of the lectins exchanged with deuterium oxide, together with model studies, provide evidence for the presence of two water molecules coordinated to the Mn2+ in all of the proteins. In contrast to concanavalin A, the absence of solvent exchange at the Mn2+ site in the pea and lentil lectins demonstrated by nuclear magnetic relaxation dispersion measurements [Bhattacharyya, L., Brewer, C.F., Brown, R. D., III, & Koenig, S. H. (1985) Biochemistry 24, 4985-4990] must therefore be due to slow exchange of the water ligands of the bound Mn2+. Binding of saccharides was observed to have little effect on the structural features of the Mn2+ site in the lectins as determined by ESEEM.
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PMID:Electron spin echo envelope modulation studies of lectins: evidence for a conserved Mn(2+)-binding site. 185 Jun 25

Heparin cofactor II (HC) is a plasma serine proteinase inhibitor (serpin) that inhibits the coagulant proteinase alpha-thrombin. We have recently demonstrated that proteolysis of HC by catalytic amounts of polymorphonuclear leukocyte proteinases (elastase or cathepsin G) generates leukocyte chemotaxins (Hoffman, M., Pratt, C. W., Brown, R. L., and Church, F. C. (1989) Blood 73, 1682-1685). One of four peptides produced when HC is degraded by neutrophil elastase has chemotactic activity for both monocytes and neutrophils with maximal migration comparable to formyl-Met-Leu-Phe, the "gold standard" bacterially derived chemotaxin. The amino-terminal sequence of this HC peptide is Asp-Phe-His-Lys-Glu-Asn-Thr-Val-... and the peptide corresponds to Asp-39 to Ile-66 of HC. A variety of synthetic peptides derived from this sequence were evaluated for leukocyte migration activity, and a dodecapeptide from Asp-49 to Tyr-60 (Asp-Trp-Ile-Pro-Glu-Gly-Glu-Glu-Asp-Asp-Asp-Tyr) was identified as the active site for leukocyte chemotactic action. The 12-mer synthetic peptide possesses significant neutrophil chemotactic action at 1 nM (60% of the maximal activity of formyl-Met-Leu-Phe), while a peptide with the reverse sequence has essentially no chemotactic activity. Cross-desensitization experiments also show that pretreatment of neutrophils with a 19-mer peptide (Asn-48 to Ile-66) greatly reduces subsequent chemotaxis to HC-neutrophil elastase proteolysis reaction products. When injected intraperitoneally in mice, the HC-neutrophil elastase digest elicits neutrophil migration. Our results demonstrate that not only does HC function as a thrombin inhibitor, but that limited proteolysis of HC near the amino terminus yields biologically active peptide(s) which might participate in inflammation and in wound healing and tissue repair processes.
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PMID:Leukocyte chemoattractant peptides from the serpin heparin cofactor II. 198 58

Phagocytosis by monocytes or neutrophils can be enhanced by interaction with several proteins or synthetic peptides containing the Arg-Gly-Asp sequence. Recently we showed that an mAb, B6H12, specifically inhibited this enhancement of neutrophil phagocytosis by inhibiting Arg-Gly-Asp binding to the leukocyte response integrin (Gresham, H. D., J. L. Goodwin, P. M. Allen, D. C. Anderson, and E. J. Brown. 1989. J. Cell Biol. 108:1935-1943). Now, we have purified the antigen recognized by B6H12 to homogeneity. Surprisingly, it is a 50-kD molecule that is expressed on the plasma membranes of all hematopoietic cells, including erythrocytes, which express no known integrins. On platelets and placenta, but not on erythrocytes, this protein is associated with an integrin that can be recognized by an anti-beta 3 antibody. In addition, both the anti-beta 3 and several mAbs recognizing the 50-kD protein inhibit Arg-Gly-Asp stimulation of phagocytosis. These data demonstrate an association between integrins and the 50-kD protein on several cell types. For this reason, we call it Integrin-associated Protein (IAP). We hypothesize that IAP may play a role in signal transduction for enhanced phagocytosis by Arg-Gly-Asp ligands.
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PMID:Integrin-associated protein: a 50-kD plasma membrane antigen physically and functionally associated with integrins. 227 87

Mutations in the plasma membrane H(+)-ATPase gene (PMA1) of Saccharomyces cerevisiae that confer growth resistance to hygromycin B have been shown recently to cause a marked depolarization of whole cell membrane potential (Perlin, D. S., Brown, C. L., and Haber, J. E. (1988) J. Biol. Chem. 263, 18118-18122). In this report, the biochemical and genetic properties of H+-ATPases from four prominent hygromycin B-resistant pma1 mutants, pma1-105, pma1-114, pma1-147, and pma1-155, are described. Single base pair changes were identified in pma1-105, pma1-114, and pma1-147 that resulted in amino acid substitutions of Ser-368----Phe, Gly-158----Asp, Pro-640----Leu, respectively. An A----G transition mutation at -39 in the 5'-untranslated region of the mRNA of pma1-155 was also found. This mutation creates an out-of-Frame upstream AUG initiation codon that apparently reduces normal translation of PMA1. DNA sequence analysis of PMA1 from strain Y55 identified 9 base pair substitutions that resulted in 6 amino acid changes in nonconserved regions when compared to the published sequence for strain S288C. Plasma membranes of three of the four pma1 mutants contained normal amounts of H(+)-ATPase; membranes from pma1-155 contained enzyme at 62% of the wild-type level. The kinetics of ATP hydrolysis were most strongly altered for enzymes from pma1-105 and pma1-147 which showed changes in both Km and Vmax. A striking pH dependence for these parameters was found for enzyme from pma1-105 which resulted in a precipitous decline in Km and Vmax below pH 6.5. ATP hydrolysis by enzymes from pma1-105 and pma1-147 was insensitive to inhibition by vanadate. These enzymes, in contrast to wild-type and vanadate-sensitive mutant enzymes, were poorly protected from trypsin-induced inactivation by MgATP and vanadate or Pi alone. These results are pertinent to the mechanism of vanadate-induced enzyme inhibition and suggest that Ser-368 and Pro-640 influence the affinity of the phosphate-binding site for Pi. All mutant enzymes catalyzed ATP-induced pH gradient formation following purification and reconstitution into liposomes. Finally, these results further demonstrate the usefulness of hygromycin B as a generalized screening tool for isolating diverse plasma membrane ATPase mutants.
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PMID:Defective H(+)-ATPase of hygromycin B-resistant pma1 mutants fromSaccharomyces cerevisiae. 253 14

Avian liver mitochondrial hydroxymethylglutaryl-CoA synthase contains an active-site cysteine involved in forming the labile acetyl-S-enzyme intermediate. Identification of and assignment of function to this cysteine have been accomplished by use of an experimental strategy that relies upon generation and rapid purification of the S-acetylcysteine-containing active-site peptide under mildly acidic conditions that stabilize the thioester adduct. Automated Edman degradation techniques indicate the peptide's sequence to be Arg-Glu-Ser-Gly-Asn-Thr-Asp-Val-Glu-Gly-Ile-Asp-Thr-Thr-Asn-Ala-Cys-Tyr. The acetylated cysteine corresponds to position 129 in the sequence deduced from cDNA data for the hamster cytosolic enzyme [Gil, G., Goldstein, J.L., Slaughter, C.A., & Brown, M.S. (1986) J. Biol. Chem. 261, 3710-3716]. The acetyl-peptide sequence overlaps that reported for a tryptic peptide that contains a cysteine targeted by the affinity label 3-chloropropionyl-CoA [Miziorko, H. M., & Behnke, C. E. (1985) J. Biol. Chem. 260, 13513-13516]. Thus, availability of these structural data allows unambiguous assignment of the acetylation site on the protein as well as a refinement of the mechanism explaining the previously observed affinity labeling of the enzyme.
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PMID:Identification of the site of acetyl-S-enzyme formation on avian liver mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase. 290 51

An acylamino acid-releasing enzyme purified from porcine liver showed peptidase activity above pH 8. Of the non-acylated peptides tested, this peptidase activity was only exerted on peptides with Gly or Ala at their N-termini. These results are consistent with the previous observations for similar enzymes from sheep red blood cells (Witheiler, J. & Wilson, D.B. (1972) J. Biol. Chem. 247, 2217-2221) and beef liver (Gade, W. & Brown, J.L. (1978) J. Biol. Chem. 253, 5012-5018). The pH dependence of the peptidase activity showed that only peptides with uncharged N-terminal amino acids such as glycyl- or alanyl-peptides act as substrates for the enzyme. These results suggest that the peptidase activity seen for the acylamino acid-releasing enzyme is an intrinsic activity of the enzyme that is triggered by misrecognition of uncharged smaller N-terminal amino acids in non-acylated peptides as acyl groups at higher pHs.
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PMID:Apparent dipeptidyl peptidase activities of acylamino acid-releasing enzymes. 634 18

Five unique phycoerythrobilin (PEB) peptides were prepared from Porphyridium cruentum B-phycoerythrin by a combination of tryptic and thermolytic digestion without alteration in the spectroscopic properties of the bilin (Lundell, D.J., Glazer, A.N., DeLange, R.J., and Brown, D.M. (1984) J. Biol. Chem. 259, 5472-5480). alpha-1 Cys(PEB)-Tyr-Arg alpha-2 Leu-Cys(PEB)-Val-Pro-Arg beta-1 Met-Ala-Ala-Cys(PEB)-Leu-Arg beta-2T Phe-Ala-Ala-Gly-Asp-Cys(PEB)-Thr-Ser (Formula: see text) where alpha and beta refer to the subunits from which the peptides were derived High resolution 1H NMR analysis of peptides alpha-2, beta-1, and beta-2T combined with earlier studies of peptide alpha-1 (Schoenleber, R.W., Leung, S.-L., Lundell, D.J., Glazer, A.N., and Rapoport, H. (1983) J. Am. Chem. Soc. 105, 4072-4076) has provided proof that all of the singly linked PEB peptides contain a thioether bond to the 3' position of ring A, and strong evidence in support of a trans-dihydro ring A in each of these chromopeptides. The circular dichroism spectra of the four singly linked PEB peptides show that the configuration at C-16 is R in each instance. The present study coupled with previously reported results on peptide beta-3T (Schoenleber, R.W., Lundell, D.J., Glazer, A.N., Rapoport, H. (1984) J. Biol. Chem. 259, 5481-5484 provides the first comprehensive analysis of the structure of all the polypeptide-linked prosthetic groups on the alpha and beta subunits of B-phycoerythrin.
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PMID:Bilin attachment sites in the alpha and beta subunits of B-phycoerythrin. Structural studies on the singly linked phycoerythrobilins. 671 55

Allophycocyanin from Nostoc sp. phycobilisomes was separated into four spectrally distinct components designated allophycocyanin I, B, II, and III by adsorption chromatography on brushite columns. Allophycocyanins I and B had red-shifted fluorescence emission maxima, and on this basis, may function in transfer of excitation energy from phycobilisomes to chlorophyll a. Allophycyanins II and III, which together comprise 70% of the total allophycocyanin, have absorption maxima at 648 nm and 650 nm, respectively, and probably transfer excitation energy from phycocyanin to allophycocyanins I and B, in addition to serving a structural function. Allophycocyanin I was resolved into alpha, beta, and gamma subunits with apparent molecular weights of 18,000, 17,000, and 35,000, respectively, whereas allophycocyanin B was resolved into two subunits with apparent molecular weights of 16,100 and 15,300, using a modified Weber and Osborn gel electrophoresis system (Brown, A. S., and Troxler, R. F. (1977) Biochem. J. 163, 571-581). In the same gel system, allophycocyanins II and III were each resolved into alpha and beta subunits with apparent molecular weights of 18,000 and 17,000, respectively. The subunits of allophycocyanins I, II, and III were isolated by gel filtration and ion exchange chromatography and the amino acid compositions determined. Automated sequence analysis demonstrated that the first 30 amino acids at the NH2 terminus of alpha subunits, and the beta subunits, of allophycocyanins I to III were identical. alpha Subunits: Ser-Ile-Val-Thr-Lys-Ser-Ile-Val-Asn-Ala-Asp-Ala-Glu-Ala-Arg-Tyr-Leu-Ser-Pro-Gly -Glu-Leu-Asp-Arg-Ile-Lys-Ser-Phe-Val-Thr- beta Subunits: Ala-Gln-Asp-Ala-Ile-Thr-Ala-Val-Ile-Asn-Ala-Ala-Asp-Val-Gln-Gly-Lys-Tyr-Leu-Asp-Ala-Thr-Ala-Leu-Ser-Lys-Leu-Lys-Ala-Tyr- The gamma subunit of allophycocyanin I and both subunits of allophycocyanin B appeared to be blocked at the NH2 terminus, suggesting that the allophycocyanin B subunits may be different gene products than those of allophycocyanins I to III, or if the same, the subunits of allophycocyanin B undergo proteolytic modification after initial synthesis.
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PMID:Allophycocyanin from Nostoc sp. phycobilisomes. Properties and amino acid sequence at the NH2 terminus of the alpha and beta subunits of allophycocyanins I, II, and III. 741 Apr 30

We have examined several peptidase activities of human multicatalytic protease (MCP) purified from the lymphoblastoid cell line 721.45 and a deletion mutant derivative, 721.174, lacking MCP subunits encoded in the major histocompatibility complex (MHC) class II region. Wild-type lymphoblast MCP hydrolyzed a specific peptide, glutaryl-Gly-Gly-Phe-4-methylcoumaryl-7-amide (-MCA), several times faster than the mutant enzyme did, suggesting that MHC-encoded subunits may provide this activity. Contrary to a recent report [Driscoll, J., Brown, M. G., Finley, D. & Monaco, J J. (1993) Nature (London) 365, 262-264], we did not detect significant aminopeptidase associated with lymphoblast MCPs. Our results also differ markedly from those of Gaczynska et al. [Gaczynska, M., Rock, K. L. & Goldberg, A L. (1993) Nature (London) 365, 264-267], who reported that gamma interferon (IFN-gamma) alters the peptidase activities of lymphoblast MCPs. We found that IFN-gamma did not produce significant differences in the peptidase activities of purified MCPs. Moreover, our measurements of Vmax and Km for succinyl-Leu-Leu-Val-Tyr-MCA hydrolysis differ 600-fold and 15-fold, respectively, from those reported by Gaczynska et al. On balance, the findings presented here do not support the idea that IFN-gamma induces major changes in the peptidase activity of purified MCPs.
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PMID:Effects of interferon gamma and major histocompatibility complex-encoded subunits on peptidase activities of human multicatalytic proteases. 783 34

The complex of Ni(II) and the tripeptide Gly-Gly-His catalyzes, in the presence of monoperoxyphthalic acid, a zero-length protein-protein cross-linking via an oxidative radical pathway involving mainly aromatic amino acids and not at all nucleophilic residues [Brown, K. C., Yang, S.-H., and Kodadek, T. (1995) Biochemistry 34, 4733-4739]. We have taken advantage of this unprecedented cross-linking system to directly and selectively probe the solution structure and functioning of the hydrophobic interface between F-actin and skeletal myosin subfragment 1 (S-1) at the level of its aromatic components, in the absence and in the presence of nucleotides (ATP and ADP) or nucleotide analogs (AMPPNP, PPi, and ADP. AlF4). Following verification of the structure of the Ni(II)-peptide chelate and of its oxidized active form by electrospray mass spectrometry, complexes of F-actin and S-1 or proteolytic S-1 derivatives and complexes of S-1 and proteolytic F-actin derivatives were readily cross-linked under various controlled conditions without apparent alteration of the acto-S-1 recognition. The covalent adducts were identified on electrophoretic gels using specific protein labeling with the oxidation-resistant fluorophor, monobromobimane, combined with immunochemical staining. Two types of actin-heavy chain conjugates were produced. One, with a mass of 180 kDa, was formed in the rigor state or with ADP bound; the other one, with a mass of 200 kDa, was generated from the ternary complexes comprising a gamma-P-containing ligand. They were accumulated with an efficiency of 8 and 6%, respectively. For each reversible complex, the 180 kDa:200 kDa band ratio was essentially as predicted from the nucleotide-dependent A to R equilibrium mechanism of the acto-S-1 interaction in solution [Geeves, A. M., and Conibear, P. B. (1995) Biosphys. J. 68, 194s-201s]. Both covalent species resulted from the cross-linking of an actin monomer to the central 50 kDa segment, and their distinct mobilities reflect gamma-P-mediated structural changes at or near the actin-50 kDa fragment interface. Peptide mapping showed the cross-linking to take place between the 506-561 S-1 segment and the 48-113 actin stretch. The localization of these regions in the atomic F-actin-S-1 model implies that nucleotide-modulated close contacts, involving aromatic residues, are operating between the C-terminal helix of the hydrophobic strong actin-binding motif of S-1 bound to the primary actin monomer and the top portion of the adjacent lower actin subunit. The specificity of the nickel-peptide cross-linking, as assessed with the acto-S-1 complex, makes it a candidate for potential general use in investigations of the hydrophobic interactions within other protein motor-based assemblies.
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PMID:Probing the hydrophobic interactions in the skeletal actomyosin subfragment 1 and its nucleotide complexes by zero-length cross-linking with a nickel-peptide chelate. 924 2


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