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

Sequential extraction of mature rabbit corneal stroma with NaCl-Tris buffer and acetic acid solubilized only 12% of the total corneal collagen. Pepsin (E:S 1:10,4 degrees C, 48 hr) in 0.4 M acetic acid solubilized 91% to 95% of the total collagen in the residue. Approximately 68% of the solubilized material could be precipitated at 2.5M NaCl and a further 3% to 9% at 3.5M NaCl. The collagenous material precipitating at 2.5M NaCl contained alpha, beta, gamma, and some higher molecular weight components and had a CNBr profile similar to bovine type I skin collagen. It had an hydroxylysine/lysine (OHLys/Lys) ratio of 0.43, similar to that of skin collagen, but unlike skin collagen was 52% glycosyled. Although the 3.5M NaCl precipitate had a CNBr peptide profile similar to that of type I collagen, it contained two additional collagen chains of molecular weight approximately 140,000 and 100,000 daltons, had an OHLys/Lys ratio of 0.62, and was 66% glycosylated. Individual chains were separated from the collagen precipitates by gel electrophoresis,and the additional collagen chains were shown to be carbohydrate rich. These additional collagen chains may be derived from one or more molecular species which are physiologically important in the maintenance of the unique organization of corneal collagen.
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PMID:Collagen polymorphism in mature rabbit cornea. 34 41

Pepsin-solubilized collagen I from skin and bone was analyzed with regard to its thermal stability as a triple helical molecule in solution and after in vitro fibril formation. Collagen I from human control bone was compared with samples showing deficiencies or surplus in the degree of hydroxylation of lysine. The helix to coil transitions were studied by circular-dichroism measurements and limited trypsin digestion. Melting of fibrils from standardized in vitro self-assembly was investigated turbidimetrically. Human control bone collagen I has a maximum transition rate (Tm) at 43.3 degrees C in 0.05% acetic acid. This is 1.9 degrees C above control skin (Tm = 41.4 degrees C), most likely, due to a higher degree of prolyl hydroxylation--0.48 in bone vs. 0.41 in skin collagen I. Lysyl overhydroxylation of human and mouse bone collagen I appears to reduce the Tm slightly (approximately 1 degree C). Underhydroxylated bone collagen has a Tm which is 2 degrees C below control. Melting temperatures of in vitro formed fibrils are an indication for higher thermostability in parallel with an increase of lysyl hydroxylation. Accordingly, the melting temperature of such fibrils from human control skin, 49.3 degrees C, exceeds control bone by 1.4 degrees C. The degree of lysyl hydroxylation in these samples is 0.14 and 0.10, respectively. Further underhydroxylation (0.06) reduced it down to 45.4 degrees C, while extensive overhydroxylation did not continue to increase the thermal stability of fibrils.
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PMID:Comparative study on the thermostability of collagen I of skin and bone: influence of posttranslational hydroxylation of prolyl and lysyl residues. 146 61

The separation of pepsin isoenzymes 1, 2, 3 and 5 (gastricsin) in human gastric juice was effected by chromatography on Mono Q ion-exchanger, and slow-moving proteinase was purified to homogeneity by using a modified procedure incorporating a novel affinity-chromatography step. The pH-activity profiles of these enzymes with mucus glycoprotein and basement-membrane substrates were determined; the profiles for pepsin 2 were noticeably different, and, in general, the pH optima for the hydrolysis of basement membrane were more acidic. Pepsin 1 expressed larger specificity constants (kcat./Km) than pepsin 3 with a series of synthetic peptide substrates, reflecting greater binding (smaller Km) by pepsin 1. Inhibitor studies at pH 1.7 and 4.5 with a series of P2-substituted lactoyl-pepstatins implied that valine at position P2 was optimal for inhibiting pepsins 1, 2 and 3 but detrimental for pepsin 5, whereas lysine at position P2 was tolerated well by pepsin 5 but not by pepsins 1, 2 and 3. The potency of lactoyl-pepstatin with lysine at position P2 did not increase as a function of pH. P2-substituted lactoyl-pepstatins failed to show any inhibitory selectivity among pepsins 1, 2 and 3.
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PMID:Substrate and inhibitor studies with human gastric aspartic proteinases. 211 Nov 33

Amino acid composition of meat-and-bone meals, poultry by-product meals, blood meals, bone meals and feather meals showed characteristic differences. Meat-and-bone meals and blood meals had surplus in lysine, whereas poultry by-product meals and feather meals were relatively rich in cystine. Blood meals had high levels of branched-chain amino acids as compared to isoleucine. In vitro pepsin digestibility of meat-and-bone meals (79.9 +/- 17.7%; n = 24) and blood meals (95.8 +/- 4.2%; n = 11) was found to be higher than that of poultry by-product meals (65.3 +/- 7.7%; n = 14) or feather meals (44.7 +/- 9.2%; n = 16). Pepsin digestibility of poultry by-product meals showed a significant negative correlation with crude protein content (r = -0.73; P less than 0.05; n = 14). However, in vitro pepsin digestibility of poultry by-product meals as well as meat-and-bone meals, blood meals and feather meals, showed insignificant correlations with NPU indices as well as with available crude protein contents of the meals. The NPU values of meat-and-bone meals for rats (29.9 +/- 11.7; n = 100) were lower than those of poultry by-product meals (52.1 +/- 7.1; n = 14). The NPU values of blood meals (6.4 +/- 5.6; n = 11) and feather meals (23.5 +/- 10.0; n = 16), determined as sole sources of protein, were low and they did not elicit weight gain in rats. The available crude protein content of poultry by-product meals (34.3 g/100 g +/- 3.6; n = 14) was higher than that of meat-and-bone meals (17.0 g/100 g +/- 7.3; n = 100).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The value of crude protein content and in vitro pepsin digestibility of abattoir by-product meals in the prediction of their available protein content. 251 10

A component, termed pyridinoline, has been reported to be derived from 'lysine aldehyde' (2,6-diaminohexanaldehyde) and designated as the stable cross-link of mature collagen. Commerically prepared collagen and freshly obtained mature bovine tendon collagen were both investigated with regard to their pyridinoline content. Both sources of material could be depleted of this component by mild washing procedures. Pepsin-solubilized collagen and peptides derived from CNBr cleavage of intact collagen did not contain the compound. Pure pyridinoline was isolated and shown to be hydrolysed by water, as previously reported, but neither hydroxylysine nor lysine could be ds not a cross-linking component of collagen.
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PMID:An investigation of pyridinoline, and putative collagen cross-link. 677 52

Single cell protein (SCP) derived from secondary clarifiers of pulp mills is a potential commercial protein supplement in many areas. Samples of SCP were collected from several pulp mills in the Pacific Northwest and evaluated by laboratory procedures. Six in vivo digestion trials were conducted to determine the relative nutritive value of SCP that was dewatered by centrifugation or by the addition of a polyacrylamide polymer before being put through a belt press and dried with a sonic dehydrator. Amino acid analyses showed that SCP was higher in methionine than was cottonseed meal (CSM) and had a similar level of lysine. True protein, based upon amino acids recovered in SCP samples, ranged from 51.6 to 65.9% of the crude protein (CP). Pepsin digestibility of the CP ranged from 16.2 to 36.8%. Pepsin digestibility increased by 6.3 to 11.3 percentage units when SCP were incubated in a buffered rumen fluid for 24 hours. Solubility of the nitrogenous components in 10% Burroughs' buffer solution ranged from 12.4 to 36.5%. The range in mineral composition was : P, .62 to 1.55%; Ca, .14 to .99%; K, .21 to 5.52%; Mg, .07 to .59%. The concentration of trace minerals and heavy metals varied considerably from sample to sample. Digestion trials were conducted with sheep to compare SCP with CSM; 20 to 50% of the total CP was provided by the SCP sources. The CP digestibilities of the centrifuged and the polymer-dewatered SCP were 70.5 to 70.8% and 66.3 to 69.9%, respectively, of that observed for CSM. In all digestion trials, sheep consumed the SCP diets readily, and no digestive disturbances were observed. On the basis of laboratory and in vivo results, pulp mill SCP has the potential to be a viable protein supplement for livestock.
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PMID:Evaluation of single cell protein from pulp mills: laboratory analyses and in vivo digestibility. 680 31

Pepsin contains a single lysine residue which protrudes from the enzyme's surface, behind the active site cleft, on the C-terminal domain. Mutations of pepsin by site-directed mutagenesis of the Lys-319 residue were generated to study the structure-function relationships. Kinetic parameters, pH activity profiles, along with conformational analysis using circular dichroism (CD), and molecular modelling were examined for the wild-type (non-mutant) and mutant enzymes. The pepsin mutations, Lys-319-->Met and Lys-319-->Glu, resulted in a progressive increase in the Km and similar decrease in kcat, respectively, as well as being denatured at a lower pH than the wild-type pepsin. CD analysis indicated that mutations at Lys-319 resulted in changes in secondary structure fractions which were reflected in changes in enzymatic activity as compared to the wild-type pepsin, i.e. kinetic data and pH denaturation study. Molecular modelling of mutant enzymes indicated differences in flexibility in the flap loop region of the active site, the region around the entrance of the active site cleft, sub-site regions for peptide binding, and in the subdomains of the C-terminal domain when compared to the wild-type enzyme. The results suggest that Lys-319, which is distal to the active site, is important to the flexibility/stability of the enzyme, as well as to its catalytic machinery.
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PMID:The sole lysine residue in porcine pepsin works as a key residue for catalysis and conformational flexibility. 765 14

An autosomal dominant mutation in the COL2A1 gene was identified in a child with the Kniest form of spondyloepiphyseal dysplasia. A C to T transition at nucleotide 35 of exon 12 changed the codon GCG for alanine 102 of the triple helical domain of alpha 1(II) chains of type-II collagen to GTG for valine. The transition also introduced a GT dinucleotide into exon 12. Analysis of cDNA prepared from Kniest cartilage showed that in vivo the transition resulted in an alternatively spliced mRNA that lacked the 213' nucleotides from exon 12. The cartilage cDNA contained approximately equal amounts of normal cDNA and shortened mutant cDNA. The deletion of 21 nucleotides from the mutant cDNA maintained the translational reading frame but resulted in the loss of alanine 102 to lysine 108, which interrupted the repetitive glycine-X-Y triplet sequence required for formation of the triple helix. Type-II collagen molecules containing one or more mutant chains were expected, therefore, to contain interrupted triple helices with a short amino-terminal helical domain A and a large carboxy-terminal helical domain B. Kniest cartilage contained a reduced amount of pepsin-solubilized type-II collagen that consisted of overmodified alpha 1(II) chains. Peptide mapping showed that the overmodifications extended to the carboxy terminus of the alpha 1(II) chains. Pepsin digestion also yielded shortened alpha 1(II) chains corresponding to helical domain B. Kniest chondrocytes cultured in alginate beads produced type-II collagen that was not stably incorporated into the pericellular matrix. This study highlights the importance of dominant negative mutations of COL2A1 in producing Kniest dysplasia.
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PMID:Alternative splicing of exon 12 of the COL2A1 gene interrupts the triple helix of type-II collagen in the Kniest form of spondyloepiphyseal dysplasia. 889 63

As part of a structure-function analysis of the higher-plant ADP-glucose pyrophosphorylase (AGP), we used a random mutagenesis approach in combination with a novel bacterial complementation system to isolate over 100 mutants that were defective in glycogen production (T.W. Greene, S.E. Chantler, M.L. Khan, G.F. Barry, J. Preiss, T.W. Okita [1996] Proc Natl Acad Sci USA 93: 1509-1513). One mutant of the large subunit M27 was identified by its capacity to only partially complement a mutation in the structural gene for the bacterial AGP (glg C), as determined by its light-staining phenotype when cells were exposed to l3 vapors. Enzyme-linked immunosorbent assay and enzymatic pyrophosphorylysis assays of M27 cell extracts showed that the level of expression and AGP activity was comparable to those of cells that expressed the wild-type recombinant enzyme. Kinetic analysis indicated that the M27 AGP displays normal Michaelis constant values for the substrates glucose-1-phosphate and ATP but requires 6- to 10-fold greater levels of 3-phosphoglycerate (3-PGA) than the wild-type recombinant enzyme for maximum activation. DNA sequence analysis showed that M27 contains a single point mutation that resulted in the replacement of aspartic acid 413 to alanine. Substitution of a lysine residue at this site almost completely abolished activation by 3-PGA. Aspartic acid 413 is adjacent to a lysine residue that was previously identified by chemical modification studies to be important in the binding of 3-PGA (K. Ball, J. Preiss [1994] J Biol Chem 269: 24706-24711). The kinetic properties of M27 corroborate the importance of this region in the allosteric regulation of a higher-plant AGP.
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PMID:Aspartic acid 413 is important for the normal allosteric functioning of ADP-glucose pyrophosphorylase. 893 21


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