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)

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 effects of various proteolytic enzymes on the high molecular weight protein (connectin) present in a direct sodium dodecyl sulfate extract of myofibrils from chicken breast muscle were studied in detail. To keep the high molecular weight proteins intact, myofibrils had to be prepared in the presence of EGTA. Trypsin, chymotrypsin, papain, and nagarse readily hydrolyzed connectin (doublet band of titin) and the band 3 protein (N2-line protein). Pepsin did not attack connectin, but digested the band 3 protein and myosin. Calcium-activated neutral proteinase hydrolyzed the band 3 protein, leaving connectin intact. On the other hand, serine protease digested connectin but not the band 3 protein.
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PMID:Connectin, an elastic protein of muscle. Effects of proteolytic enzymes in situ. 702 43

A collagenous protein could be precipitated by (NH4)2SO4 from the culture medium of a murine teratocarcinoma-derived cell line (Ko, C.Y., Johnson, L.D. and Priest, R.E. (1979) Biochim. Biophys. Acta 581, 252-259). Further purification of this protein was achieved by combining DEAE-cellulose chromatography with either CM-cellulose or molecular sieve chromatography. The collagenous polypeptides had subunit molecular weights of 160 000, if determined by molecular sieve chromatography, or 190 000, if determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and they are not linked by disulphide bridges. Amino acid composition of this collagen is similar to that of a murine type IV collagen isolated from EHS sarcoma (Timpl et al. (1978) Eur. J. Biochem. 84, 43-52). The most prominent peptides resulting from cleavage of the protein by CNBr had estimated molecular weights of 25 000, 23 000, 11 700 and 9400. Pepsin treatment of this collagen under non-denaturing conditions produced three major fragments having molecular weights of 70 000, 45 000 and 43 000. We conclude that the collagen secreted by the murine teratocarcinoma-derived cell culture is a type IV basement membrane collagen. Therefore, this culture system should provide a continuous source of type IV collagen, which may be used to study the interaction of this collagen with other basement membrane components.
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PMID:Purification and characterization of a collagenous protein secreted by a murine teratocarcinoma-derived cell line. 710 99

Gastric fistula rats (n = 79) were either left as unstressed (fistula closed) controls or gastric secretion, microcirculation (MBF), mucosal stress ulcers were studied in secretory rats subjected to zero (= freely movements allowed), mild, severe restraint stress for 8 h. In all rats gastrin in portal vein and aorta was measured in addition after discontinuation of either protocol. Acid secretion and MBF are progressively reduced by increasing stress. Pepsin and sodium are elevated with severe, acid concentration with mild stress. Pepsin and sodium are elevated with severe, acid concentration with mild stress. Serum gastrin (controls - aorta 53+/- SEM 5, portal vein 73 +/- 9 pg/ml) rises sharply in portal and systemic blood with institution of acid diversion via the outside (zero stress - 136 +/- 21, 398 +/- 98 pg/ml), but declines with increasing stress (severe stress - 82 +/- 16, 101 +/- 27 pg/ml) despite otherwise identical experimental conditions. It is concluded that (1) acid secretion rate and MBF are lowered by stress, but stress ulcers are associated with either increased acidity (mild stress) or peptic activity (severe stress) of gastric juice in the absence of elevated gastrin, (2) enhanced sodium fluxes via gastric lumen and lower acid suggest disruption if mucosal barrier by severe stress, and (3) restraint stress ulcers may be the expression of a combination of disturbances, mainly of metabolic and endocrine nature.
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PMID:Gastric secretion, mucosal erosions and porto-systemic gastrin gradients as influenced by different degrees of stress in the rat. 732 53

The changes in rates of hydroxyproline formation and biosynthesis of types-I and -III collagen during bone matrix-induced sequential differentiation of cartilage, bone and bone marrow in rat were investigated. Biosynthesis of types-I and -III collagen at different stages of this sequence was studied by labelling in vivo and in vitro with [2,3-3H]proline. Pepsin-solubilized collagens were separated by sodium dodecyl sulphate/polyacrylamide-slab-gel electrophoresis. The results revealed that maximal amounts of type-III collagen were synthesized on day 3 during mesenchymal-cell proliferation. Thereafter, there was a gradual decline in type-III collagen synthesis. On days 9--20 during bone formation predominantly type-I collagen was synthesized. Similar results were obtained by the use of labelling techniques both in vivo and in vitro.
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PMID:Changes in synthesis of types-I and -III collagen during matrix-induced endochondral bone differentiation in rat. 739 43

Pepsin (3.6 nmol) was detected by the following three-step procedure: (i) reaction with a 20-fold molar excess of BO-IMI (a fluorophore containing a reactive imidazole group) in the presence of a 150-fold molar excess of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 2% sodium dodecyl sulfate; (ii) gel filtration (spin column) to remove most of the residual BO-IMI; and (iii) capillary electrophoresis with laser-induced fluorescence detection. For the latter step, 8.5 x 10(-7) of the original sample was injected. BO-IMI/EDC targets phosphomonoesters and does not label albumin (prior knowledge). Progressive dephosphorylation of pepsin with acid phosphatase reduced its labeling with BO-IMI. Thus, the BO-IMI, as intended, labels the phosphate group on pepsin. Such BO-IMI labeling should be useful in general for studying phosphoproteins and phosphopeptides.
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PMID:Phosphate-specific fluorescence labeling of pepsin by BO-IMI. 750 26

Out of fourteen compounds reported here only four [N-valproyl GABA (V.GABA), N-phthaloyl GABA (P.GABA), gamma-phthalimido N-amyl butyramide (PGA) and gamma-phthalimido N-phenyl butyramide (PGP)] gave significant protection to all the four components of maximal electroshock-induced seizures (MES) in mice. It appeared that substitution of either amino or carboxylic or both groups of gamma-aminobutyric acid (GABA) with bulkier groups like aliphatic or aromatic carbons usually produced effective anticonvulsant GABA derivatives. V.GABA and P.GABA were the most effective anticonvulsant GABA derivatives in protecting all the components of MES-induced seizures. They were 2.3 and 1.5 times potent than sodium valproate in molar ratio, but P.GABA has low therapeutic index when compared to V.GABA. The observed anticonvulsant activity may be due to enhanced GABA concentration in the CNS. Probably, the active compound (V.GABA) crossed the blood brain barrier and hydrolysed to GABA and valproic acid to bring about its anticonvulsant action.
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PMID:Effect of GABA analogues on various components of maximum electroshock-induced seizures in mice. 807 Aug 45

As bovine collagen is currently being scrutinized as to its immunogenicity in clinical use, a human source collagen, human amnion collagen (HAC), has been developed in our laboratory as an injectable biomaterial for soft tissue augmentation. Pepsin-extracted human amnion collagen was highly purified and reconstituted. Gamma irradiation was employed to ensure complete sterility and to produce cross-linking in collagen chains to improve implant persistence without the use of chemical additives. The purity and characteristics of human amnion collagen were proven by amino acid assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immune blotting, and collagenase digestion. Animal studies comparing both irradiated and nonirradiated amnion collagen to bovine collagen (Zyderm and Zyplast) were carried out in a rat model. Humoral immunity was evaluated by examining the sera for antibody reactivity towards the implanted human collagen by the ELISA test. Insignificant antibody levels against human amnion collagen were found. Animal observation revealed fibroplasia, vascular infiltration, and the development of adipocytes with the implant as well as a lack of inflammatory response following up to 12 months of implantation. The persistence rate of our human amnion collagen was equal to, or even longer than, that of both types of bovine collagen implants.
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PMID:Human amnion collagen for soft tissue augmentation--biochemical characterizations and animal observations. 812 34

To investigate the nature of the 140 kDa glycoprotein in the trabecular meshwork, polypeptides were extracted with either urea/sodium dodecyl sulfate (SDS)/beta-2-mercaptoethanol (BME) or guanidine hydrochloride followed by pepsin digestion. After electrophoresis and immunoblotting with anti-type-VI-collagen antibodies, a single fraction of molecular weight 140 kDa was identified in the urea/SDS/BME extracts. Pepsin solubilization revealed two immunoreactive fractions (molecular weights 75 and 85 kDa) that comigrated with purified, pepsin-solubilized type VI collagen. By using the polymerase chain reaction (PCR) and primers specific for the alpha 2(VI) chain of type VI collagen, a single PCR product was obtained, which corresponded to the expected size of 137 base pairs, from the total RNA extracted from the trabecular meshwork ex vivo. Southern hybridization with the antisense oligonucleotide probe of the alpha 2(VI) chain confirmed that the amplified sequence was specific. The results show that the trabecular meshwork contains a significant amount of type VI collagen and that trabecular cells express the mRNA coding for the alpha 2(VI) chain of this glycoprotein. The presence of type VI collagen in the trabecular meshwork is implicated in cell-extracellular matrix interactions at this site, and its abnormal accumulation in glaucomatous and aging eyes probably signifies a defect in the function of the trabecular cells in these eyes.
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PMID:Identification of type VI collagen in the trabecular meshwork and expression of its mRNA by trabecular cells. 815 10

Pepsin successfully catalyzed the synthesis of several hydrophobic octa- and decapeptides in dimethylformamide-water solutions containing concentrated urea at pH 4.65. The factors that influence peptide synthesis in the presence of urea were studied using condensation of the tripeptides Z-Ala-Ala-Phe-OH and H-Leu-Ala-Ala-OCH3 as a model. The dependence of Z-Ala-Ala-Phe-Leu-Ala-Ala-OCH3 yield on pepsin concentration and pH, as well as the behavior of pepsin during peptide synthesis were studied. It was shown that pepsin catalyzed the synthesis of Z-Ala-Ala-Phe-Leu-Ala-Ala-OCH3 in guanidine hydrochloride and sodium dodecyl sulfate solutions. Other proteinases, subtilisin and thermolysin, were applied for the synthesis of p-nitroanilides of tri- and tetrapeptides in urea solutions. Proteinase-catalyzed peptide synthesis in the presence of denaturing agents might help to overcome the limitations caused by poor solubility of the starting peptide derivatives, although this effect is sometimes counterbalanced by the product solubility.
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PMID:Proteinase-catalyzed peptide synthesis in concentrated solutions of urea and other denaturing agents. 890 96


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