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)

The residues 90-92 can be split off from the C-terminal region of the isolated alpha-subunit of choriogonadotropin (residues 88--92: -Tyr-Tyr-His-Lys-Ser-OH) by means of serine carboxypeptidase (des-Lys91,Ser92-alpha-subunit; des-(90-92)-alpha-subunit). However, when choriogonadotropin is digested by serine carboxypeptidase, only the residues 143-145 (-Leu-Pro-Gln-OH) form the C-terminus of the beta-subunit are released (des-(143-145)-choriogonadotropin). Depending on the pH conditions, glutamine 145 and the residues 143-145, respectively, are liberated by digestion of the isolated beta-subunit (des-Gln145-beta-subunit and des-(143-145)-beta-subunit, respectively). The present study provides evidence that the C-termini of both the isolated subunits and those in choriogonadotropin are probably arranged on the surface of the molecules. The biological activity of des-(143-145)-choriogonadotropin is not significantly decreased. The immunological activity, however, is reduced when measured by complement fixation. In comparison to the native hormone, a four-fold amount of des-(143-145)-choriogonadotropin has to be applied to obtain highest complement fixation. The conformation of des-(143-145)-choriogonadotropin does not seem to differ from that of the native hormone, when estimated both by CD measurements and by Ans-choriogonadotropin fluorescence. The respective determinant therefore seems to depend, at least to some extent, on the sequence of the C-terminal region of the beta-subunit of the hormone; complement fixation, however, does not seem to be affected significantly, when the des-(143-145)-beta-subunit is compared with the native beta-subunit using an antiserum against the native beta-subunit. This provides evidence that this C-terminal determinant is possibly more immunogenic at the hormone than at the isolated beta-subunit. The biological activity of recombined choriogonadotropin in vivo as well as in vitro is markedly reduced when serine 92 is removed from the C-terminus of the alpha-subunit (des-Ser92,Lys91-alpha-native beta-subunit: 36% residual activity in vivo). Biological activity is lost when the residues 88-90 are removed by digestion of the des-Ser92,Lys91-alpha-subunit with carboxypeptidase A. Recombination products between a modified alpha-and the native beta-subunit show a reduced Anschoriogonadotropin fluorescence (des-Lys91,-Ser92-alpha + native beta-subunit: 52%; des-(88-92)-alpha- + native beta-subunit: 23%). The Ans-induced aggregation of choriogonadotropin, however, also takes place in those recombination products which display a low Ans-choriogonadotropin fluorescence, indicating that the reduction is probably not caused by a portion of the molecules losing their binding sites for Ans. Therefore the diminished Ans-choriogonadotropin fluorescence seems to signal small conformational changes. The CD spectra of the native and the des-(90-92)-alpha-subunit, however, seem not to differ significantly. It is shown that the release of amino acids from the C-terminus of the alpha-subunit causes a disturbance of the interaction between the subunits. This seems to prevent an effective conformational change of the beta-subunit which probably is a prerequisite for the binding of the hormone to the receptors of Leydig cells.
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PMID:Studies of the specific role of the subunits of choriogonadotropin for biological, immunological and physical properties of the hormone. Digestion of choriogonadotropin and its isolated subunits with serine carboxypeptidase. 52 40

Coupling of bovine carboxypeptidase A with diazotized 5-amino-1H-tetrazole increases esterase activity, decreases peptidase activity slightly, and modifies one tyrosyl residue. Subsequent nitration of the azoenzyme has no further effect on esterase activity, decreases peptidase activity markedly, and modifies a second tyrosyl residue. Analysis of the azopeptides isolated from a chymotrypsin digest of the doubly modified enzyme by affinity, ion exchange, and high pressure liquid chromatography indicates that the principal residue modified by diazo-1H-tetrazole is Tyr-248. Analysis of the nitropeptides isolated by similar procedures indicates that nitration occurs mainly at Tyr-198. This residue becomes susceptible to modification only as a consequence of a conformational change that accompanies azo coupling of Tyr-248. These results describe a unique example of the influence of protein structure on the reactivity of functional amino acid residues and illustrate an important aspect of chemical modification of enzymes.
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PMID:Functional tyrosyl residues of carboxypeptidase A. The effect of protein structure on the reactivity of tyrosine-198. 56 10

A series of monocarboxylic and dicarboxylic acid sulfur-containing by-product analogues of lysine and arginine has been synthesized and tested as competitive inhibitors of bovine carboxypeptidase B. The most effective derivatives were guanidinoethylmercaptosuccinic acid and aminopropylmer-captosuccinic acid with Kis of 4 and 8 X 10(-6) M, respectively. Kinetics studies established the pure competitive nature of the inhibition. Mixed studies with the alkylating reagents bromoacetyl-D-arginine and bromoacetamidobutylguanidine established their efficiency in protecting the active-center glutamic acid and tyrosine of bovine carboxypeptidase B, respectively, from irreversible alkylation. Kinetic studies with bovine carboxypeptidase A and porcine carboxypeptidase B showed a lack of efficiency for A and high degree of efficiency for B.
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PMID:By-product analogues for bovine carboxypeptidase B. 61 98

Comparison of various chloroplast-type ferredoxin sequences, chemical and enzymic modifications, reconstitution experiments, and fluorescence measurement of chloroplast-type ferredoxins have led to the following conclusions. 1. Tyrosine, histidine, and tryptophan residues are not directly involved in the oxidation-reduction mechanism of ferredoxins. The four indispensible cysteine residues in spinach ferredoxin which constitutes a part of the iron-sulfur cluster are located at residues 39, 44. 47 and 77. Two out of six cysteine residues in Spirulina ferredoxin could be easily modified with vinylpyridine without the loss of reconstitutive ability i.e. the apoferredoxin could be converted to the holoform by the addition of iron and sulfide. 2. Spinach ferredoxin was digested with carboxypeptidase A and the terminal alanine could be removed without loss of the spectral properties of native ferredoxin. However, the removal of the terminal three residues gave rise to the loss of reconstitutive ability. 3. The amino groups of spinach ferredoxin were modified by acetic anhydride and four residues were acetylated. The acetylated preparation of ferredoxin had an unique spectrum. Upon the addition of high concentration of ions the spectrum of this derivative resembled the spectrum of native ferredoxin. Acetylferredoxin did not combine with ferredoxin-NADP reductase, but upon the addition of moderate concentrations of cations, it did bind to this enzyme.
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PMID:Structure and function of chloroplast-type ferredoxins. 78 73

A proposed mechanism for the catalytic hydrolysis of peptide bonds by acid proteases is similar in many respects to the Zn-carbonyl mechanism previously derived for carboxypeptidase A. In the acid proteases the electrophilic component is the proton shared by Asp-32 and Asp-215; Tyr-75 donates its proton to the amide nitrogen of the scissile bond and an OH- ion from a water molecule bound between the carboxyl group of Asp-32 and the substrate attacks the carbonyl carbon atom.
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PMID:Mechanism of acid protease catalysis based on the crystal structure of penicillopepsin. 89 39

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

Nitration of bovine carboxypeptidase A crystals with tetranitromethane increases esterase activity, decreases peptidase activity, and modifies about one tyrosyl residue. Modification of enzyme crystals avoids the polymerization that occurs when the enzyme is nitrated in solution. Two procedures have been employed to identify the tyrosyl residues nitrated. The first involves cyanogen bromide cleavage and isolation of the fragment containing residues 104-301. After solubilization by succinylation, this fragment is digested with chymotrypsin, the peptides are fractionated by gel filtration, and the nitrotyrosyl peptides are purified by affinity chromatography on an antinitrotyrosyl antibody-Sepharose conjugate followed by ion-exchange chromatography. In the second, the nitroenzyme is heat denatured, digested by chymotrypsin, and fractionated on the affinity and ion-exchange columns. By both methods, the major mitropeptides, representing between 60 and 80% of the nitrotyrosyl label, are uniquely compatible with that segment of the sequence of carboxypeptidase containing Tyr-248. A nearby cation, either the active site zinc ion or Arg-145, would seem to be an important factor in determining the selective nitration of this residue.
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PMID:Chemical modification of carboxypeptidase A crystals. Nitration of tyrosine-248. 94 53

Five amino acid residues, i. e. serine, lysine, histidine and two tyrosine residues, are split from the C-end of the alpha-subunit of bovine luteinizing hormone by carboxypeptidase A. Gel-filtration through Sephadex G-100 demonstrated that the carboxypeptidase-treated alpha-subunit is not recombined with the native beta-subunit and does not form complex molecules of the hormone.
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PMID:[Important role of C-terminal amino acid sequence of the luteinizing hormone alpha-subunit in its recombination with the beta-subunit]. 102 94

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


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