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)

Several features of carboxypeptidase A (CPA) which were previously established by the X-ray diffraction structure studies have now been confirmed by the chemical sequence analysis. These results include the number (307) of amino acid residues in CPA(alpha), the identities of the residues (Arg 145, Glu 270, and Tyr 248) shown by the X-ray study to be involved in substrate binding and catalysis, and the existence of a disulfide bond. The Zn ligands, shown by the X-ray study to be residues 69, 72, and 196 and identified as His, Glx, and either Glx or Lys, are proved by the chemical sequence to be His, Glu, and His, respectively. No change is required in our previous mechanistic deductions, which are here extended to include a specific mechanism of activation of the substrate by a net charge on the metal ion, which suffers a change in local dielectric constant when it is covered by a substrate.
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PMID:The structure of carboxypeptidase A. IX. The x-ray diffraction results in the light of the chemical sequence. 526 13

Coupling of carboxypeptidase A crystals with diazotized arsanilic acid specifically labels tyrosine 248, an active-site residue of the enzyme. Many azophenols are yellow and their zinc complexes are red; the "yellow" absorption spectrum of zinc arsanilazocarboxypeptidase crystals is characteristic of the arsanilazotyrosyl group, not of the zinc complex. This is consistent with the interpretation of x-ray data on native crystals of carboxypeptidase A, indicating that tyrosine 248 and the zinc atom are too far apart to form a complex. However, the enzyme in solution is red, denoting the formation of a complex between zinc and arsanilazotyrosine 248. The most likely interpretation of the data is that the orientation of arsanilazotyrosine 248 in solution and in the crystal is different. If the unlabeled tyrosine 248 of native carboxypeptidase undergoes similar changes, these data may bear upon the low activity of the enzyme in the crystalline state and on the catalytic mechanism of the enzyme based on the crystal structure. The opportunities for analogous spectrochemical studies of other, similar systems are pointed out.
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PMID:Differences between the conformation of arsanilazotyrosine 248 of carboxypeptidase A in the crystalline state and in solution. 528 87

1. Urease of specific activity 160-180 Sumner units/g. (Sumner, 1951) was purified from jack-bean meal. The preparation was pure on the basis of polyacryl-amide-gel electrophoresis and N-terminal studies. 2. By using both the 1-fluoro-2,4-dinitrobenzene method and the phenyl isothiocyanate method a single N-terminal methionine residue was found. 3. A single C-terminal sequence -Tyr-Leu-Phe was found by studies with carboxypeptidase A, carboxypeptidase B and hydrazinolysis. 4. N-Bromosuccinimide cleavage showed that five unique tryptophan sequences were present: Trp-Ala, Trp-Glu, Trp-Gly, Trp-Met and Trp-Arg. 5. Polyacrylamide-gel electrophoresis in sodium dodecyl sulphate showed that urease had a subunit molecular weight of 76000. 6. The yield of N- and C-terminal amino acids, the number of tryptic peptides and tryptophan sequences and the above polyacrylamide-gel electrophoretic measurement all suggest that urease contains a single structural subunit of molecular weight 75000.
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PMID:The subunit structure of jack-bean urease. 538 87

A carboxypeptidase purified from brain catalyzes the release of COOH-terminal tyrosine without further digesting tubulin. It is distinct from previously described carboxypeptidases, and appears to have specificity for tubulin as it is not inhibited by peptides and proteins with COOH-terminal tyrosine, and because, unlike carboxypeptidase A (which by removing tyrosine from aldolase causes its inactivation), this enzyme does not decrease aldolase activity. The enzyme detyrosinolates both self-assembly-competent (cycle-purified) and -incompetent (phosphocellulose-purified) tubulin. However, under assembly conditions the rate was 2-3-fold higher for competent tubulin. Preincubation of assembly-competent tubulin with podophyllotoxin or colchicine resulted in a parallel concentration-dependent inhibition of tubulin polymerization and detyrosinolation. Similarly, when incompetent tubulin was induced to polymerize by preincubation with purified microtubule-associated protein 2 (an assembly-promoting protein) or taxol, the initial rate of its detyrosinolation increased 3-5-fold, and this increase was blocked if podophyllotoxin was also added along with microtubule-associated protein 2 or taxol during the preincubation. Oligomers induced by adding vinblastine to incompetent tubulin were also detyrosinolated more rapidly, and the stimulation was abolished by maytansine, which has been shown to disperse the vinblastine-induced oligomers. When polymerized and subunit fractions were separated after a steady state mixture had been partially digested with the carboxypeptidase, the former was found to have lost 2-3 times more COOH-terminal tyrosine. Although both polymer and monomer can be detyrosinolated by the enzyme, polymeric and oligomeric forms are the preferred substrates. Carboxypeptidase appeared to release tyrosine at the same rate from populations of short and long microtubules.
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PMID:Preferential action of a brain detyrosinolating carboxypeptidase on polymerized tubulin. 611

Comparative studies of the activity of somatostatin and of several of its analogues in releasing histamine from rat mast cells suggest that the integrity of the positively charged amino terminus and of lysines at positions four and nine of somatostatin may be necessary to preserve its histamine releasing activity. D-Lys4 substitution reduced activity by 80% while D-Lys9 substitution increased it four fold. Replacement of the amino terminal Ala by Tyr or simultaneous removal of Ala1,Gly2 and the amino portion of the now terminal Cys3 inhibited the activity by about 95%. Finally, dihydrosomatostatin retained 33% activity while an analogue where both Cys sulfur atoms were permanently blocked by acetamidomethyl groups retained only about 13% activity. Using information from these studies and from the literature, two-dimensional and space-filling models approximating the conformation of somatostatin were constructed and compared with a plausible corresponding model of the hexameric form of 48/80, the most active congener of this classic mast cell secretagogue. By such modelling it was possible to show that the orientation of the cationic moieties in the two molecules could be similarly arranged thereby perhaps explaining the ability of these compounds to induce mast cell secretion.
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PMID:Mast cell histamine secretion in response to somatostatin analogues: structural considerations. 617 34

The mast cell degranulating capacity of neurotensin and three of its fragments was examined. In Tyrode solution (137 mM NaCl, 2.7 mM KCl, 0.4 mM NaH2PO4, 1.4 mM CaCl2, 1 mM MgCl2, 10 mM Hepes, 5.6 mM glucose, pH 7.4), neither intact neurotensin nor its C-terminal tripeptide (Tyr-Ile-Leu) caused any release of histamine. Concentrations of neurotensin exceeding 10(-4)M did cause histamine release but through lysis of the cells. The C-terminal hexa- and octapeptides of neurotensin (Arg-Arg-Pro-Tyr-Ile-Leu and Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu, respectively) induced a non-cytolytic release of histamine with the latter peptide being more active (ED50 = 90 microM for the hexapeptide and 13 microM for the octapeptide). This release was not affected by the C-terminal tripeptide. It was found to be calcium-dependent and was inhibited by the anti-allergic drug, disodium cromoglycate. Phosphatidylserine did not enhance release of histamine and saturation of the immunoglobulin E (IgE) receptors did not inhibit it.
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PMID:Structure-activity relationship in the mast cell degranulating capacity of neurotensin fragments. 618 72

This study concerned the fragmentation of beta-endorphin (beta-EP-(1-31) by synaptic membrane-bound peptidases. The peptides which accumulated during digestion of beta-endorphin by isolated synaptosomal plasma membrane preparations of rat brain were separated and isolated by high pressure liquid chromatography. Amino acid analysis of the peptide fractions indicated the formation of beta-EP-(1-21), beta-EP-(2-21) (pH 7.4), beta-EP-(18-31), beta-EP-(1-14), and beta-EP-(1-13) (pH 5.0) in addition to previously identified gamma-endorphin (beta-EP-(1-17)), alpha-endorphin (beta-EP-(1-16), and their des-tyrosine fragments (Burbach, J. P. H., Loeber, J. G., Verhoef, J., Wiegant, V. M., De Kloet, E. R., and De Wied, D. (1980) Nature 283, 96-97). The beta-endorphin fragments obtained with crude or with purified synaptosomal plasma membranes differed only quantitatively. The peptidase which converted gamma-endorphin into beta-EP-(1-16), beta-EP-(1-15), beta-EP-(1-14), and beta-EP-(1-13), was considerably active at pH 5.0 and resembled carboxypeptidase A in degrading gamma-endorphin; the activity was reduced by the carboxypeptidase A inhibitor D-phenylalanine. The data supplement previous findings and allow routes to be delineated for the conversion of beta-endorphin by brain synaptic membranes. A pathway comprising the main events in the conversion processes is proposed and is discussed in relationship to the significance of beta-endorphin as a precursor for neuropeptides with distinct central activities.
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PMID:Proteolytic conversion of beta-endorphin by brain synaptic membranes. Characterization of generated beta-endorphin fragments and proposed metabolic pathway. 627 86

The carboxy-terminal amino acids of a number of poliovirus proteins were determined by carboxypeptidase A analysis. The nonstructural proteins P3-2, P3-4b and their precursor. P3-1b, were found to be coterminal with a sequence of -Ser-Phe-COOH. As these proteins are coded for at the extreme 3' end of the viral RNA, it is possible to establish the termination site of translation at nucleotide 7,361, 73 nucleotides before the start of the polyadenylic acid tract of the RNA. Two additional nonstructural proteins, P2-X and its precursor, P2-3b, were also found to be coterminal with a sequence of -Phe-Gln-COOH. This result confirms the existence of at least one Gln-Gly proteolytic cleavage site. These Gln-Gly cleavage sites are predicted from the nucleotide sequence to be ubiquitous throughout the poliovirus genome. The only exceptions are the cleavage sites at the carboxy termini of the structural protein VP4 and VP1. Carboxypeptidase A analysis of VP1 establishes a terminal sequence of -Thr-Tyr-COOH, and similar analysis of VP4 shows Asn to be the terminal amino acid residue, observations that prove the existence of the exceptional C-terminal amino acids. In none of the analyzed cases has C-terminal trimming after cleavage been observed.
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PMID:Carboxy-terminal analysis of poliovirus proteins: termination of poliovirus RNA translation and location of unique poliovirus polyprotein cleavage sites. 628 38

Penicillinase from Bacillus cereus 569/H was purified to homogeneity. Its active site was probed by use of an affinity label generated in situ by the diazotization of 6-aminopenicillanic acid, a catalytically poor substrate for this enzyme. The loss of activity arising during the inactivation is dependent upon pH and the penicillin:sodium nitrite ratio used. Optimal inactivation was obtained at pH 4.7 and reactivation could be prevented if subsequent purification and manipulations were performed at low pH. Inactivation by diazotized 6-aminopenicillanic acid was characterized further by tryptic and chymotryptic digestion of the inactivated enzyme and peptide mapping of the resulting digests. Amino acid analysis of the chymotryptic labeled peptide yielded a composition which corresponds to residues 41-46 (Ala-Phe-Ala-Ser-Thr-Tyr) in the published partial sequence of the enzyme (Thatcher, D. (1975) Biochem. J. 147, 313-326). Further digestion of this chymotryptic peptide with carboxypeptidase A reveals that serine-44 is modified in this affinity labeling procedure. Mass spectral analysis of the modified serine residue and alkali-released label, and comparison with spectra of model compounds indicates that the inactivation occurs with rearrangement of the beta-lactamthiazolidine structure to a dihydrothiazine.
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PMID:Bacillus cereus 569/H penicillinase serine-44 acylation by diazotized 6-aminopenicillanic acid. 630 23

Acid acetone extracts of caudate nucleus from bovine brain were found to contain an amidated opioid octapeptide with the following structure: Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-NH2. The peptide has been named metorphamide. Bovine metorphamide appears to be derived by proteolytic cleavage from proenkephalin, the common precursor to [Met5]enkephalin and [Leu5]enkephalin. The cleavage within the precursor giving rise to the carboxyl terminus of metorphamide occurs at a single arginine residue and is followed by transformation of a carboxyl-terminal glycine into an amide group. Metorphamide was detected in bovine caudate nucleus extracts by radioimmunoassay, and it was purified to homogeneity by gel filtration and reversed-phase high performance liquid chromatography. Amino acid composition analysis and automated Edman degradation in the gas-phase sequencer confirmed the postulated amino acid sequence. Carboxyl-terminal amidation of bovine metorphamide was shown by stability to carboxypeptidase A digestion and full crossreactivity in a radioimmunoassay that required the carboxyl-terminal amide as part of the recognition site. A synthetic replicate of metorphamide as well as several synthetic analogs were tested for opioid activity in several bioassays and binding assays, and metorphamide was found to have a high mu-binding activity. Metorphamide is the only known naturally occurring opioid peptide that has a high mu-binding activity. The kappa-binding activity is approximately equal to 50% that of the mu-binding activity, but delta-binding activity is negligible.
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PMID:Metorphamide: isolation, structure, and biologic activity of an amidated opioid octapeptide from bovine brain. 631 61


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