Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The reactivities of phenylglyoxal (PGO), glyoxal (GO), and/or methylglyoxal (MGO) with several proteins, including ribonuclease A [EC 3.1.4.22] and its derivatives, alpha-chymotrypsin [EC 3.4.21.1], trypsin [EC 3.4.21.4], lysozyme [EC 3.2.1.17], pepsin [EC 3.4.23.1], rennin [EC 3.4.23.4], thermolysin, and insulin and its B chain, have been examined. From analyses of the reaction products, PGO was shown to be the most specific for arginine residues. GO and MGO also reacted rapidly with arginine residues, but they also reacted with lysine residues to a significant extent. A side reaction with N-terminal alpha-amino groups was observed with each of these reagents. 2. Two arginine residues out of four in ribonuclease A, two out of three in alpha-chymotrypsin, one out of two in trypsin, one out of two in pepsin, and one out of five in rennin appeared to react with PGO fairly rapidly, indicating a difference in the relative accessibility of these residues by the reagent. Extensive modification of the arginine residues by PGO occurred with RCM-derivatives of ribonuclease A and insulin B chain. The N-terminal isoleucine residues of alpha-chymotrypsin and trypsin appeared to be unreactive with PGO because of salt bridge formation with an aspartyl residue. The activity of alpha-chymotrypsin toward N-benzoyl-L-tyrosine ethyl ester and the lytic activity of lysozyme were lost rapidly on treatment with PGO, as in the case of ribonuclease A. Pepsin and rennin were only partially inactivated by reaction with PGO.
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PMID:Further studies on the reactions of phenylglyoxal and related reagents with proteins. 32 41

Pepsin was shown to catalyze synthesis of esters or p-nitroanilides tri-, tetra-, penta- and hexapeptides of general formula Z-X-Y-B, where X = Ala-Phe, Phe-Met, Ala-Ala-Glu, Ala-Ala-Phe, Ala-Ala-Leu, Ala-Ala-Trp, Ala-Ala-Met. Y = Ala, Leu, Val, Phe, Arg, Ala-Ala, Gly-Gly, Leu-Ala-Ala, Phe-Ala-Ala. B = OMe, pNA. The reactions were carried out in dimethylformamide-water solutions at pH 4.6 by equimolar ratio of amino- and carboxyl components (with the exception of Arg-pNA taken in 2-fold excess). The amount of pepsin in the reaction approached 1:1700 enzyme: substrate molar ratio although it might be improved--up to 1:3.10(5) for relatively long peptides.
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PMID:[Pepsin in the enzymatic synthesis of esters and n-nitroanilide peptides]. 144 35

According to the comparison of amino acid sequence between PGA (Penicillin G Acylase) and PBPs (Penicillin Binding Protein), We suggest that No. 565-595 peptide fragment in beta-subunit of PGA may be a substrate-binding site of enzyme. Plasmid pTZGA was constructed by cloning the 2.6 kb PGA gene of pWGA into phagemid pTZ18U The technique of site-specific mutagenesis was used to study the role of residue No. 579 (Ser) and No. 580 (Arg) of PGA. Four kinds of mutants were obtained (Ser579-->Gly579, Arg580-->Gly580, Arg580-->Glu580, Arg580-->Lys580), both Glu580 and Gly580 mutants showed no activity of enzyme and Lys580 mutant remained 30% and Gly579 mutant kept 70% activity of wilde type. The same protein expression of four mutants according to the results of ELISA indicate that mutation does not affect the expression of PGA, but Arg580 residue may be essential for substrate-binding or catalysis of PGA.
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PMID:[Studies on the function of Ser579 and Arg580 in beta-subunit of penicillin G acylase with the method of site-specific mutagenesis]. 147 18

Pepsin-solubilized collagen VI was prepared from human placenta and used to separate three constituent chains for determining partial amino acid sequences. Antibodies raised against the chains assisted in the identification and purification of several cDNA clones from three expression lambda gt11 libraries. Most of the clones hybridized to either a 3.5-kb or 4.2-kb mRNA species which by matching peptide and nucleotide sequences could be identified as coding for the alpha 2(VI) or alpha 1(VI) chain, respectively. Other clones hybridized to either an 8.5-kb mRNA which very likely encoded the alpha 3(VI) chain or to an unknown 2.0-kb mRNA. Northern blots revealed a considerable variation in the mRNA levels for each collagen VI chain in both skin and cornea fibroblasts and in several tumor cell lines. Limited sequence data generated from peptides and cDNA clones demonstrated a characteristic cysteine pattern at the junction between N-terminal globular domain and triple helix in all three chains. In addition, the data showed occasional interruptions of triplet sequences within the triple-helical domain and the presence of two Arg-Gly-Asp sequences which are potential cell-binding structures.
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PMID:Characterization of three constituent chains of collagen type VI by peptide sequences and cDNA clones. 366 27

Apolipoprotein AI of human high-density lipoproteins is secreted by hepatocytes as a proapolipoprotein with a N-terminal hexapeptide sequence (Arg-His-Phe-Trp-Gln-Gln-) which differs from the prosequence of rat apolipoprotein AI (Trp-Asp-Phe-Trp-Gln-Gln). The two proteins have in common the unusual cleavage site -Gln-Gln-Asp-Glu-. It is hydrolysed by a specific serum proteinase with the release of mature apo AI. We synthesized a model substrate for the study of the final processing of pro-apo AI by the serum proteinase. It is an undecapeptide embracing the human pro-hexapeptide sequence and the first five N-terminal residues of apo AI, covalently linked to a hydrophilic resin. The N-terminal arginine residue was 3H-labelled. [formula; see text] This sequence was not cleaved by human serum under the conditions under which rat serum processes the pro-form of apo AI secreted by rat hepatocytes. Pepsin and chymotrypsin fragmented the undecapeptide at sites characteristic for these proteinases. We conclude that the proteolytic cleavage at the specific site (-Gln-Gln-Asp-Glu-) requires the correct conformation in addition to the specific amino-acid sequence.
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PMID:Processing of proapolipoprotein AI requires specific conformation. 392 Oct 42

Pepsin catalyzes numerous acyl-transfer reactions. Are peptic acyl-enzyme intermediates involved in such reactions? To start, we examine the cleavage of Leu-Trp-Met-Arg at pH 3.4-4.5 in the presence of 25 mM tryptophanamide. Substantial amounts of Leu-TrpNH2 are generated. However, the appearance of this acyl-transfer product cannot be attributed to the intervention of Leu-pepsin and its trapping by tryptophanamide. Experiment proves that Leu-Trp-Met-Arg affords Leu3, which, in turn, reacts with tryptophanamide to produce Leu-TrpNH2. Both the formation of Leu3 from Leu-Trp-Met-Arg and the conversion of Leu3 + tryptophanamide into Leu-TrpNH2 can potentially implicate the generation and trapping of a Leu-pepsin intermediate. Does experiment support either possibility? The answer is no. Our data show that most of the Leu3 derived from Leu-Trp-Met-Arg stems from an autocatalytic condensation process whereby Leu3 already present speeds the conversion of the leucine residues of unreacted Leu-Trp-Met-Arg into more Leu3. Technical problems have prevented us from determining whether the first Leu3 formed results from the trapping of an acyl-enzyme intermediate. The generation of Leu-TrpNH2 from Leu3 was studied primarily via a more tractable analogous reaction: Leu-Trp-Leu + tryptophanamide leads to Leu-TrpNH2. The mechanism governing these transformations is highly complex. Its major feature is an initial condensation between two molecules of substrate. All the examples investigated further illustrate the marked tendency of pepsin to catalyze condensation reactions between suitably constructed small peptides. The prevalence of these reactions complicates the interpretation of much data bearing on pepsin's mechanism of action.
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PMID:Surprising consequences of the tendency of pepsin to catalyze condensation reactions between small peptides. 640 22

An inhibitor I-1, capable of acting on both alpha-amylase and trypsin, was purified to homogeneity from ragi (finger-millet) grains. The factor was found to be stable to heat treatment at 100 degrees C for 1 h in the presence of NaCl and also was stable over the wide pH range 1-10. Pepsin and Pronase treatment of inhibitor I-1 resulted in gradual loss of both the inhibitory activities. Formation of trypsin-inhibitor I-1 complex, amylase-inhibitor I-1 complex and trypsin-inhibitor I-1-amylase trimer complex was demonstrated by chromatography on a Bio-Gel P-200 column. This indicated that the inhibitor is 'double-headed' in nature. The inhibitor was retained on a trypsin-Sepharose 4B column at pH 7.0. Elution at acidic pH resulted in almost complete recovery of amylase-inhibitory and trypsin-inhibitory activities. alpha-Amylase was retained on a trypsin-Sepharose column to which inhibitor I-1 was bound, but not on trypsin-Sepharose alone. Modification of amino groups of the inhibitor with 2,4,6-trinitrobenzenesulphonic acid resulted in complete loss of amylase-inhibitory activity but only 40% loss in antitryptic activity. Modification of arginine residues by cyclohexane-1,2-dione led to 85% loss of antitryptic activity after 5 h, but no effect on amylase-inhibitory activity. The results show that a single bifunctional protein factor is responsible for both amylase-inhibitory and trypsin-inhibitory activities with two different reactive sites.
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PMID:Natural plant enzyme inhibitors. Characterization of an unusual alpha-amylase/trypsin inhibitor from ragi (Eleusine coracana Geartn.). 679 40

The pools of Arg, Gly, His, Ile, Ser, Glu, Leu, Val and Asp were lower during photosynthesis at 1% O2 concentration. At the same time specific radioactivity of a number of amino acids--following 14CO2 incorporation--was different than that at atmospheric O2 concentration. This is probably due to the inhibition of the photorespiratory nitrogen cycle and the resulting NH+4 deficiency. The pattern of response to O2 concentration suggests that in rye plants in the light, all Gly and a part of Ser are synthesized by an O2-sensitive pathway, i.e. via the glycolate pathway, but most of Ser is probably formed from 3-phosphoglycerate (3-PGA) via the O2-insensitive pathway. Changes in the pool size and specific radioactivity after 6 h incubation in darkness suggest that synthesis of Gly is strongly light-dependent, whereas synthesis of Ser was substantial also in darkness. The specific radioactivity of Ala, Asp, Ser and Glu indicates that in darkness those amino acids are formed from a common precursor, i.e. glycolytic 3-PGA, and undergo rapid metabolic turnover.
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PMID:Photosynthesis in detached rye leaves at normal and low oxygen concentration. II. Incorporation of 14CO2 into amino acids. 681

Procathepsin B from the parasitic trematode Schistosoma mansoni was expressed as a glycosylation-minus mutant in yeast cells and purified by means of a histidine affinity tag which was added to the carboxyl terminus of the recombinant protein. The purified zymogen underwent autoprocessing but required an assisting protease for activation. Pepsin-activated schistosomal cathepsin B was further characterized with the cathepsin B-specific substrates N-benzyloxycarbonyl (Z)-Arg-Arg-p-nitroanilide, Z-Arg-Arg-7-amido-4-methyl-coumarin, and Z-Phe-Arg-7-amido-4-methylcoumarin. A proteolytic activity comparable to mammalian cathepsin B was observed. In addition, we analyzed the degradation of human hemoglobin by schistosomal cathepsin B, which has been suggested to be the physiological target of the protease.
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PMID:Cathepsin B of Schistosoma mansoni. Purification and activation of the recombinant proenzyme secreted by Saccharomyces cerevisiae. 857 74

We analyzed the tissue-type plasminogen activator (TPA)-binding proteoglycans (PGs) on human umbilical vein endothelial cells (HUVECs), which were metabolically labeled with [35S]NA2SO4. Cell extracts were then prepared and subjected to affinity chromatography on diisopropyl fluorophosphate (DFP)-inactivated TPA-Sepharose 4B. Approximately 6% of the incorporated 35S radioactivity bound to DFP-treated TPA-Sepharose 4B and was eluted with 2 mol/L NaCl. In addition to NaCl, heparin, arginine, and lysine but not glycine, epsilon-amino-n-caproic acid or aspartic acid inhibited this binding and eluted the bound 35S radioactivity. Urea-containing polyacrylamide gel electrophoresis of the eluted material consistently revealed two main signals of 35S radioactivity (one with an M(r) between 600,000 and 750,000 [PGA] and the other with an M(r) between 120,000 and 180,000 [PGC]). Occasionally a less intense signal with an M(r) between 340,000 and 440,000 (PGB) was seen. Heparitinase treatment markedly decreased the intensities of both 35S signals (PGA and PGB), and chondroitinases AC and ABC abolished the 35S signal of PGC, indicating that most of the HUVEC-incorporated radioactivity with an affinity for TPA could be attributed to heparan sulfate- and chondroitin sulfate-like structures. Reductive elimination, which was performed to separate the possible glycosaminoglycan moieties from the core proteins, confirmed the PG-like nature of this material and again revealed heparan sulfate and chondroitin sulfate as the major glycosaminoglycan components. We therefore conclude that HUVECs synthesize TPA-binding, heparan sulfate- and chondroitin sulfate-containing PGs. In vivo, similar PGs may play a role in TPA binding to endothelial cells and thereby possibly influence TPA activity and/or provide an intravascular storage pool of TPA.
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PMID:Isolation and characterization of tissue-type plasminogen activator- binding proteoglycans from human umbilical vein endothelial cells. 896 24


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