Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

3,3-Diphenylpropanoate (DPP) activates the carboxypeptidase A catalyzed hydrolysis of benzoylglycyl-L-phenylalanine (BzGly-L-Phe) (Ka = 2.1 x 10 (-3) M) and inhibits ester hydrolysis uncompetitively (K1 =2.1 X 10 (-3) M). A common modifier binding site located adjacent to the peptide and ester substrate binding sites is proposed. The forms of the pathways proposed for activation and inhibition are remarkably similar.
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PMID:Mechanisms for activation and inhibition of carboxypeptidase A catalyzed hydrolyses of peptides and esters. 66 84

In an attempt to understand the role of nickel in jack bean urease (1), we turned to a variety of other enzymes important in the utilization, production, or transfer of ammonia. We found several, including the L-histidine and L-phenylalanine ammonialyases and some enzymes that utilize glutamine or ammonia in amidotransferase reactions, all of which show evidence for the involvement of as yet unreported transition metal ions in their mechanism of action. We support the view that catalysis by metalloenzymes may be a reflection of the chemistry of the metal ion itself as a Lewis acid, and that perhaps too much emphasis has been placed on supposed special characteristics (such as strains, "entasis") of the enzyme-metal ion association. In this context, we have discussed the mechanism of catalysis of hydrolysis of specific substrates by carboxypeptidase A, and have returned to urease to examine the role of nickel in its mechanism of action.
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PMID:Metal ions in enzymes using ammonia or amides. 76 57

Human carboxypeptidase A has been isolated from activated pancreatic juice by means of affinity chromatography employing the competitive inhibitor benzylsuccinic acid as an affinity ligand. The structural and functional features of the human and bovine enzymes are quite analogous. The molecular weights of human and bovine carboxypeptidases A are virtually identical, their amino acid compositions are similar, both contain 1 g-atom of zinc/mole, and the activities of both are restored by addition of zinc to the apoenzyme. The inhibition of human carboxypeptidase by chelating agent is reversed by either dilution or addition of a metal such as Cu2+. When other metals are substituted for the native zinc, peptidase activity of the human metallocarboxypeptidases follows the order: cobalt greater than nickel greater than manganese greater than cadmium, while the sequence for esterase activities is: manganese greater than cobalt = cadmium greater than nickel. The latter sequence differs from that observed for the bovine enzyme. Human carboxypeptidase A crystallizes after dialysis at low ionic strength. Hydrolysis of the dipeptide carbobenzoxyglycyl-L-phenylalanine and of the ester benzoylglycyl-L-alpha-hydroxy-beta-phenyllactate exhibits kinetic anomalies, but that of their longer homologues does not. Chemical modifications with tyrosine reagents alters esterase and peptidase activities. The affinity chromatographic method here described should greatly facilitate future studies of this enzyme from human and other sources.
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PMID:Purification and crystallization of human carboxypeptidase A. 93 22

The mechanism of action of a carboxypeptidase inhibitor from potatoes has been probed by studying its interaction with derivatives of carboxypeptidase A containing modified residues at the active site. Arsanilazocarboxypeptidase A, a derivative containing a chromophore attached to tyrosine 248, exhibits a circular dichroism spectrum which is sensitive to the presence of ligands at the active site (Kagan, H.M., and Vallee, B.L. (1969), Biochemistry 8, 4223). Since the spectral change attending binding of the carboxypeptidase inhibitor to arsanilazocarboxypeptidase A is similar to that produced by small substrates and inhibitors, the enzyme-inhibitor interaction also involves the enzyme active site. Catalytic activity is not required for inhibitor binding. Complexes of the inhibitor with apocarboxypeptidase A anc carboxypeptidase A which was inactivated by treatment with the affinity label, N-bromoacetyl-N-methyl-L-phenylalanine, are demonstrated by gel filtration experiments. Morever, competitive binding studies reveal that the latter derivative, in which the binding pocket is presumably blocked by reagent, binds inhibitor nearly as strongly as does the native enzyme, and differences in free energy of association being only 0.4 kcal/mol of a total binding energy of - 11 kcal/mol. A model is proposed to account for both the tight binding of inhibitor to the N-bromoacetyl-N-methyl-L-phenylalanine derivative and the involvement of the active site of arsanilazocarboxypeptidase A. It is suggested that the inhibitor fits into a shallow depression at the active site of the enzyme but does not penetrate into the binding pocket.
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PMID:Carboxypeptidase inhibitor from potatoes. Interaction with derivatives of carboxypeptidase A. 93 26

The NH2- and COOH-terminal sequence of nuclear portein A24 has been determined by automatic Edman degradation and carboxypeptidase A and B digestion. Protein A24 is of interest because it is composed in part of histone 2A (Goldknofp, I.L., and Busch, H., (1975) Biochem, Biophys. Res. Commun. 65, 951-960). The sequence of the first 37 NH2-terminal residues is: Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly-Lys-Thr-Ile-Thr-Leu-Glu-Val-Glu-Pro-Ser-Asp-Thr-Ile-Glu-Asn-Val-Lys-Ala-Lys-Ile-Gln-Asp-Lys-Glu-Gly-Ile-Pro- This sequence is not homologous to any known histone sequence. It contains regions of internal homology (italics). The COOH-terminal amino acid sequence is the same as that of histone 2A, naely: -His-His-Lys-Ala-Lys-Gly-Lys-COOH.
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PMID:The NH2- and COOH-terminal amino acid sequence of nuclear protein A24. 97 47

An asymptomatic woman was found to have a compensated hemolytic state due to an unstable hemoglobin variant, comprising 35% of the total. Peptide maps of tryptic digests of the abnormal beta chain were identical to those of beta A except that tryptic peptide 15 (Tyr-His-COOH) was absent and a new peptide was detected, containing equivalent amounts of Ser, Ile, Thr, and Lys. Its sequence was determined by manual Edman degradation. An additional hydrophobic peptide isolated by counter-current distribution contained: Asx, Ser, Ala, Tyr, 2 Phe, and 3 Leu. Its sequence was determined on an automatic solid phase sequencer. Digestion with carboxypeptidase A confirmed the C-terminal sequence. Hemoglobin Cranston has an elongated beta chain with the following structure: (see article). This variant is the first "adult" human hemoglobin known to contain isoleucine. It is likely that hemoglobin Cranston arose because of a nonhomologous crossover of two normal beta chain genes, probably during meiosis, with the insertion of two nucleotides (AG) at position 144, resulting in a frame shift. Hemoglobin Cranston provides new information on the structure of the beta chain gene as well as an explanation of both the structure and genetic basis of hemoglobin Tak, the only other elongated beta chain variant that has been described.
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PMID:Hemoglobin Cranston, an unstable variant having an elongated beta chain due to nonhomologous crossover between two normal beta chain genes. 105 49

Although optical resolution of alpha-methylphenylalanine (alpha-Me-Phe) has been achieved by the action of carboxypeptidase A on the N-trifluoroacetyl derivative of the amino acid (TFA-alpha-Me-Phe), it is improbable that an alpha-methyl substrate could bind in the same orientation as glycyl-L-tyrosine, due to steric interaction of the alpha-methyl group with an atom in the imidazole ring of zinc ligand His-196. The kinetic parameters for TFA-alpha-Me-Phe and for an ester substrate bearing an alpha-methyl group (beta-hippuryl-alpha-methylphenyllactic acid, HMPL) have been determined and compared to those for the appropriate nonmethylated control substrates. Both TFA-alpha-Me-Phe and HMPL appear to be bound nearly as well as are their respective controls, and HMPL is hydrolyzed nearly as rapidly as its control. TFA-alpha-Me-Phe, however, is hydrolyzed only about one-fiftieth as rapidly as is the nonmethylated substrate. These findings are consistent with the possibilities that: (1) the proposed substrate-induced conformational shift of Tyr-248 is hindered when the methylated substrates are bound; (2) the orientation in which alpha-methyl substrates are bound precludes optimal positioning of Tyr-248 and the scissile bond even after the rotation of Tyr-248 has occurred; (3) amides and esters are bound in different orientations, and in the amide orientation an alpha-methyl group is so directed as to interfere with the approach of Glu-270 to the scissile bond.
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PMID:alpha-Methyl substrates of carboxypeptidase A. A steric probe of the active site. 114 72

The complete covalent structure of a small, basic protein with cardiotoxic activity is described. This has been isolated from the venom of Naja nigricollis by gel filtration on Sephadex G-75 and gradient ion exchange chromatography on Bio-Rex 70. The cardiotoxin, molecular weight 6806 from amino acid composition, consists of 60 amino acids, cross-linked by four disulfide bridges, connecting 3-21, 14-38, 42-53, and 54-59. The protein contains one residue of tryptophan, phenylalanine, and glutamic acid, two residues of arginine and tyrosine, four residues of methionine, and nine residues of lysine. Histidine is absent. The chymotryptic peptides of the oxidized and S-carboxymethylated protein were isolated by gel filtration on Sephadex G-25 and zone electrophoresis on a cellulose column. The sequence was determined by Edman degradation, using the (manual) direct phenylthiohydantoin method and with the use of carboxypeptidase A. Disulfide pairing was determined on thermolysin cleaved peptides from the native protein. The sequence is shown to be homologous to other cardiotoxins and a lytic factor from snake venoms and also shows homology, both in sequence and disulfide pairing to neurotoxins. A partial reduction experiment in the absence of denaturing agent using 14-C-labeled iodoacetic acid as S-carboxymethylating agent shows that disulfide bonds 14-38 and 42-53 were reduced fastest followed marginally by 54-59, and then bond 3-21.
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PMID:The complete covalent structure of a cardiotoxin from the venom of Naja nigricollis (African black-necked spitting cobra). 114 81

The initial rates of hydrolysis of Bz-Gly-Lys and Bz-Gly-Phe by carboxypeptidase B (CPB) are increased in the presence of the modifiers beta-phenylpropionic acid, cyclohexanol, Bz-Gly, and Bz-Gly-Gly. The hydrolysis of the tripeptide Bz-Gly-Gly-Phe is also activated by Bz-Gly and Bz-Gly-Gly, but none of these modifiers activate the hydrolysis of Bz-Gly-Gly-Lys, Z-Leu-Ala-Phe, or Bz-Gly-phenyllactic acid by CPB. All modifiers except cyclohexanol display inhibitory modes of binding when present in high concentration. Examination of Lineweaver-Burk plots in the presence of fixed concentrations of Bz-Gly has shown that activation of the hydrolysis of neutral and basic peptides by CPB, as reflected in the values of the extrapolated parameters, Km(app) and kcat, occurs by different mechanisms. For Bz-Gly-Gly-Phe, activation occurs because the enzyme-modifier complex has a higher affinity than the free enzyme for the substrate, whereas activation of the hydrolysis of Bz-Gly-Lys derives from an increase in the rate of breakdown of the enzyme-substrate complex to give products. Cyclohexanol differs from Bz-Gly and Bz-Gly-Gly in that it displays no inhibitory mode of binding with any of the substrates examined, activates only the hydrolysis of dipeptides by CPB, and has a greater effect on the hydrolysis of the basic dipeptide than on the neurtal dipeptide. Moreover, when Bz-Gly-Lys is the substrate, cyclohexanol activates its hydrolysis by CPB by increasing both the enzyme-substrate binding affinity and the rate of the catalytic step, an effect different from that observed when Bz-Gly is the modifier. The anomalous kinetic behavior of CPB is remarkably similar to that of carboxypeptidase A, and is a good indication that both enzymes have very similar structures in and around their respective active sites. A binding site for activator molecules down the cleft of the active site is proposed for CPB to explain the observed kinetic behavior.
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PMID:Effect of modifiers on the hydrolysis of basic and neutral peptides by carboxypeptidase B1. 117 Sep 27

The active site of angiotensin-converting enzyme (ACE) has been shown by chemical modification to contain a critical tyrosine residue, identified as Tyr-200 in human testis ACE (hTACE). We have expressed a mutant hTACE containing a Tyr-200 to Phe mutation. The mutant exhibits a marked decrease in kcat: 15-fold and 7-fold for the hydrolysis of furanacryloyl-Phe-Gly-Gly and angiotensin I, respectively, whereas its Km increases by only 1.6- and 2.2-fold, respectively. We conclude that Tyr-200 is not required for substrate binding. Instead, the effect on kcat together with a 100-fold decrease in affinity for the ACE inhibitor lisinopril indicates that Tyr-200 may participate in catalysis by stabilizing the transition state complex. Thus, Tyr-200 in hTACE has a role analogous to that of Tyr-198 in carboxypeptidase A.
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PMID:The functional role of tyrosine-200 in human testis angiotensin-converting enzyme. 131 88


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