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)

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

Collagen was isolated by acetic acid extraction in the presence of protease inhibitors and also by pepsin digestion from the skins of dogs affected with the Ehlers-Danlos syndrome and the skins on non-affected dogs. The collagen preparations isolated by acetic acid extraction from the Ehlers-Danlos syndrome-affected dog skin contained a greater proportion of alpha-chains than the collagen preparations from the normal dog skin. When the collagen from the Ehlers-Danlos syndrome-affected dog skin was reduced with NaBH4 before heat denaturation, and electrophoresis, there was a greater proportion of beta-chains present. The collagen isolated from the normal dog skin was not affected by the NaBH4 reduction. Collagen preparations isolated by pepsin digestion from both the Ehlers-Danlos syndrome-affected dog skin and the non-affected dog skin contained the same quantity of alpha- and beta-chains. In addition, collagen from both affected and non-affected dog skins isolated by pepsin digestion contained 10-11% type III collagen as determined by the interrupted sodium dodecyl sulfate polyacrylamide gel electrophoresis method. Pepsin digestion of the collagens isolated by acetic acid extraction in the presence of protease inhibitors from the skins of affected and non-affected dogs eliminated the differences between the alpha:beta ratios of the affected and non-affected collagen preparations.
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PMID:Isolation of collagen from the skins of Ehlers-Danlos syndrome-affected dogs by acetic acid extraction and pepsin digestion. 677 75

Digestion of 18S and 14S acetylcholinesterase from eel electric organ with pepsin at 15 degrees C for 6 h results in extensive degradation of the catalytic subunits, but a major portion of the collagen-like tail structure associated with these enzyme forms resists degradation. The pepsin-resistant structures partially aggregate and can be isolated by gel exclusion chromatography on Sepharose CL-6B in buffered 1 M sodium chloride. The largest structure, denoted F3, has a molecular weight of 72 000 according to gel electrophoresis in sodium dodecyl sulfate and is composed of three 24 000 molecular weight polypeptides linked by intersubunit disulfide bonds. This structure is largely, but not completely, a collagen-like triple helix as indicated by a circular dichroism spectrum typical of triple-helical collagen and an amino acid composition characterized by 27% glycine, 5% hydroxyproline, and 5% hydroxylysine. Continued pepsin action results in degradation of the disulfide linkage region such that disulfide-linked dimers F2 and finally F1 monomers become the predominant forms in sodium dodecyl sulfate. Digested samples in which either F3 or F2 predominate have virtually identical circular dichroic spectra and amino acid compositions and generate similar diffuse 24 000 molecular weight polypeptides following disulfide reduction. Thus the intersubunit disulfide linkages in F3 must occur close to the end(s) of the fragment polypeptide chains. Pepsin conversion of F3 to F2 is particularly accelerated between 25 and 30 degrees C, suggesting that the triple-helical structure in the disulfide linkage region undergoes thermal destabilization in this temperature range. Digestion at 40 degrees C yields presumably triple-helical F1 structures devoid of disulfide linkages, although their degradation to small fragments can be detected at this temperature. The question of whether the three tail subunits that give rise to F1 polypeptides are identical remains open.
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PMID:Characterization of pepsin-resistant collagen-like tail subunit fragments of 18S and 14S acetylcholinesterase from Electrophorus electricus. 678 73

The susceptibility of human type V collagen to several neutral proteases was examined. Thrombin cleaved both the alpha 1(V) and alpha 2(V) chains of this protein at 34 degrees C, producing two pairs of fragments with apparent molecular weights of 95000 and 10000 on sodium dodecyl sulfate--polyacrylamide gel electrophoresis. Two-dimensional 125I-labeled peptide mapping of the larger fragments demonstrated that the upper band [which comigrated with alpha 1(I)] was derived from both the alpha 1(V) and alpha 2(V) chains, while the other component [which comigrated with alpha 2(I) was a product of alpha 1(V) alone. Cleavage of type V collagen, containing alpha 3(V) chains, with thrombin produced an analogous pattern with three high molecular weight bands. Chymotrypsin and trypsin cleaved type V collagen at 37 degrees C but not at lower temperatures. Digestion of type V collagen with elastase at 37 degrees C resulted in selective proteolysis of alpha 2(V), leaving alpha 1(V) essentially intact. Pepsin treatment of type V collagen from which alpha 2(V) had been removed by elastase treatment resulted in nearly complete degradation of alpha 1(V). These data support the hypothesis that a major fraction of native type V collagen is a heteropolymer with the chain composition [alpha 1(V)]2 alpha 2(V). Cleavage of type V collagen by thrombin may have physiologic significance in that breakdown of pericellular matrix may be an important step in the response of a tissue to injury.
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PMID:Susceptibility of type V collagen to neutral proteases: evidence that the major molecular species is a thrombin-sensitive heteropolymer, [alpha 1(V)]2 alpha 2(V). 679 86

Subfractions of human glomerular basement membrane isolated by enzymatic procedures were analyzed for their chemical structure and biological activity. Pepsin or collagenase digestion of purified basement membranes released three groups of components: collagenous and noncollagenous fractions and also a mixed material consisting of a proteolysis-resistant association between collagen sequences and heteropolysaccharidic glycopeptides. These different fractions were explored in vitro for their ability to interact with cell membranes. In fact, only fractions containing the heterogenous material agglutinated human transformed or embryonic cells within 2 h. The cell agglutination was specifically inhibited by N-acetylosamines and N-acetylneuraminic acid. An additional incubation of 20 h at 37 degrees C of the agglutinated cells, maintained in a minimal medium devoid of serum, led to a morphological change of the transformed cells due to an increased cell adhesion and cell spreading. These experimental data suggest that the basement membrane possesses active sites - consisting of an association between collagen and structural glycoproteins - which could play a primordial role in cell matrix interactions.
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PMID:Chemical characterization and functional role of human glomerular basement membrane components. 679 4

The present study was designed to compare collagen synthesized by rabbit lens epithelial cells in culture with rabbit lens capsule collagen. Confluent monolayers of rabbit lens epithelial cells were established. Incorporation of [3H]-proline into glycoproteins secreted into the medium and cell surface components were analyzed in the presence of protease inhibitors. Gel filtration chromatography on sodium dodecyl sulfate--agarose (Bio-gel A-5m) of [3H]-labeled newly synthesized proteins by lens epithelial cells in culture resolved into a single precursor of approximate molecular weight of 160,000 daltons. Neither the medium nor the cell layer showed any evidence of low-molecular weight hydroxyproline-containing material. Limited pepsin digestion of this material cleaved the higher molecular weight chains into smaller components ranging from 25,000 to 110,000 daltons. Pepsin digestion and direct extraction of the collagenous components of the rabbit lens capsule revealed materials of high--molecular weight proteins similar to that synthesized in culture. Low--molecular weight (55,000 daltons) protein was only detected in lens capsules after prolonged pepsin digestion. S-Carboxylation of the lens capsules collagens did not affect their mobilities, but repepsinization gave rise to 110,000 dalton protein, although no significant changes in the amino acid composition were noticed. The absence of synthesis of low--molecular weight protein by cell culture and the presence of low--molecular weight components only after prolonged pepsin digestion of lens capsule could be the result of unusual susceptibility of the basement membrane collagens to pepsin attack.
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PMID:Structure and biosynthesis of rabbit lens capsule collagen. 681 26

The pyrene-labeling of acid-soluble (type I) and acid-insoluble collagens from young and old rat tail tendon has been investigated. The pyrene excimer fluorescence is associated with stabilized pyrene labels bound to two adjacent aldehydes in monomeric young collagens. Polymeric young collagens, as well as monomeric and polymeric old collagens, tend to lose this specific arrangement. This is shown by salt and new chromatographic fractionation of monomeric and polymeric collagens. During denaturation, pyrene labels are released from saturated aldehydes in both alpha 1 and alpha 2 chains. This unstable pyrene-labeling is stabilized by NaBH4 reduction of the hydrazone bonds between aldehyde groups and pyrene-containing hydrazines. This stabilization reveals that alpha 1 contains more aldehyde groups than does alpha 2 in young collagen. Pepsin-solubilized, acid-insoluble collagens are partly cross-linked and, like acid-soluble collagens, exhibit the fluorescence of pyrene aggregates probably located at unidentified cross-links, different from unsaturated aldehyde-containing cross-links in acid-soluble collagens.
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PMID:Cross-linking and fluorescence of pyrene-labeled collagen. 682 79

Chronic pyelonephritis was induced in young adult cats by the intravenous injection of a human or a feline strain of Escherichia coli after ligation of one ureter for 24 or 48 h. In the 3 cats infected with the feline strain, scarred kidneys from the obstructed side were removed at necropsy 3, 4 and 5 months later. Collagen was extracted from pyelonephritic and normal kidney tissue with dilute acetic acid and limited proteolysis with pepsin. Scarred kidneys gave higher yields of both acid-soluble collagen (normal = 0.57 +/- 0.12 mg per g tissue; scarred = 0.88 +/- 0.10 mg per g tissue) and pepsin-solubilized collagen (normal = 9.69 +/- 1.79 mg per g tissue; scarred = 20.02 +/- 2.84 mg per g tissue). There was no significant increase in the collagen yield from the kidneys of the 2 cats in which mild focal lesions were found 14 and 16 months after infection with the human strain of E. coli. Pepsin released collagens were separated by fractional salt precipitation and identified by agarose gel chromatography and polyacrylamide gel electrophoresis. Normal kidney was shown to contain collagen of Types I, IV and V (AB). The Type IV collagen extracted consisted of a mixture of 4 major pepsin-resistant chains of apparent molecular weights of 150 000, 115 000, 85 000 and 60 000. The collagen extracted from scarred kidneys was predominantly Type I, only trace amounts of Type IV and V components being present. These findings suggest that basement membrane collagens of the kidney are selectively degraded during the atrophy and scarring of chronic feline pyelonephritis and are preferentially replaced by interstitial Type I collagen.
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PMID:Experimental pyelonephritis in the cat: 3. Collagen alterations in renal fibrosis. 684 96

Intima collagen was obtained from pepsin digests of human placenta in two forms, which differ to some extent in the size of their constituent polypeptide chains (Mr 50 000-70 000). These chains are connected by disulphide bonds to large aggregates. The aggregates are arranged in a triple-helical conformation with a remarkably high thermal stability (Tm 41-62 degrees C) and are resistant to further proteolytic digestion. Reduction of as little as 5% of the disulphide bonds produces mainly monomeric triple helices (Mr about 160 000) with Tm 32 degrees C. Partially reduced material can be separated into triple-helical and non-collagenous domains by proteolysis. Pepsin releases a collagenous component with chains of Mr 38 000. Bacterial collagenase liberates two non-collagenous segments (Mr 15 000-30 000) rich in cystine. Treatment with collagenase before reduction separates intima collagen into a large fragment composed of collagenous (Tm 41 degrees C) and non-collagenous structures and a single non-collagenous segment. The data support the electron-microscopical model of intima collagen [Furthmayr, Wiedemann, Timpl, Odermatt & Engel (1983) Biochem. J. 211, 303-311], indicating that the basic unit of the fragment consists of a continuous triple helix joining two globular domains.
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PMID:Structural diversity and domain composition of a unique collagenous fragment (intima collagen) obtained from human placenta. 687 Aug 34

Maternally administered folic acid antagonists (x-methyl-PGA and 9-methyl-PGA) are known to produce various skeletal malformations in the neonate. These defects are thought to be due in part to abnormal metabolism and/or deposition of various extracellular matrix components, i.e., collagen and glycosaminoglycans. Experimental reduction of glycosaminoglycan biosynthesis in vitro has been shown previously to alter the spatial orientation and normal pattern of collagen fibrillogenesis. Furthermore, dietary withdrawal of folic acid concomitant with maternal administration of 9-methyl-PGA has been shown to result in abnormal collagen, uronic acid, and hexosamine metabolism by fetal limbs. In the present study pregnant rats were exposed to a transitory folic acid deficiency from day 11 to 14 of gestation and fetal tibias (mid-diaphyseal region) were examined with the electron microscope on day 18 of gestation. Although we were unable to ascertain any aberrant patterns of fibrillogenesis and orientation with respect to collagen, this particular teratogenic regimen resulted in an altered pattern of chondrocyte development when observed at the ultrastructural level.
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PMID:Effect of a synthetic folic acid analogue, 9-methyl-pteroylglutamic acid, on fetal chondrogenesis: ultrastructural observations. 687 Dec 96


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