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)

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

Human nucleus pulposus and annulus fibrosus, obtained at autopsy from patients 7-30 years of age, were extracted with 2 M guanidine-HCl (pH 5.82) to remove proteoglycans, then stirred with pepsin in 0.5 M acetic acid, followed by three 24-h extractions with 1 M NaCl (pH 7.5) and one 24-h extraction with 2 M KSCN (potassium thiocyanate) (pH 7.2). Pepsin and NaCl solubilized an average of about 30% of nucleus pulposus collagen and 18% of annulus fibrosus collagen. KSCN extracted a further 34% of nucleus pulposus collagen and only 4% of annulus fibrosus collagen. CM-cellulose chromatography of nucleus and annulus collagen purified from the pepsin, NaCl and KSCN supernatants consistently revealed only one peak, always appearing slightly ahead of the alpha1 position for rat tail tendon type I collagen. Polyacrylamide and SDS-gel electrophoresis consistently revealed only one band with the mobility of alpha1 chains. Amino acid composition of collagen from nucleus and annulus is comparable to those of mammalian and avian cartilage type II collagen, and distinctly different from those of rat tail tendonand guinea pig skin type I collagens. Periodate oxidation of nucleus and annulus collagens showed that 81% and 67%, respectively, of the hydroxylysine residues survive treatment, compared to 71% for bovine articular cartilage collagen and 17% for guinea pig skin collagen. Total hexose analysis revealed 1.8 muM and 2.0 muM hexose per muM periodate-stable hydroxylysine in nucleus and annulus collagens, respectively. Ion exchange chromatography showed the presence of glucose and galactose in a ratio of 0.92:1 in nucleas collagen and 1.07:1 in annulus collagen. Pepsin-solubilized, NaCl-extracted collagen from nucleus and annulus formed native-type fibrils in vitro. The banding patterns of ATP-induced segment-long-spacing precipitates of nucleus and annulus collagens were identical to each other and indistinguishable from those of cartilage (type II) collagen, but distinctly different from those of rat tail tendon (type I) collagen. These data suggest that the collagen which can be extracted after limited pepsin attack of human nucleus and annulus is of the form [alpha1 (II)]3.
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PMID:Pepsin-solubilized collagen of human nucleus pulposus and annulus fibrosus. 78 25

Selection of ideal laser parameters for tissue welding is inhibited by poor understanding of the mechanism. We investigated structural changes in collagen molecules extracted from rat tail tendon (> 90% type I collagen) after tissue welding using an 808 nm diode laser and indocyanine green dye applied to the weld site. Mobility patterns on SDS-PAGE were identical in the lasered and untreated tendon extracts with urea or acetic acid. Pepsin incubation after acetic acid extraction revealed a reduction of collagen alpha and beta bands in lasered compared with untreated specimens. Circular dichroism studies of rat tail tendon showed absence of helical structure in collagen from lasered tendon. No evidence for covalent bonding was present in laser-treated tissues. Collagen molecules are denatured by the laser wavelength and parameters used in this study. No significant amount of helical structure is regenerated on cooling. We conclude that non-covalent interactions between denatured collagen molecules may be responsible for the creation of tissue welding.
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PMID:Changes in type I collagen following laser welding. 140 2

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

Pepsin-treated type I collagen fibrils were reconstituted by warming to 37 degrees C in the presence of DOPA at a concentration of 1 x 10(-3)M. Following a 1-1.5-h lag period the "gels" became progressively stabilized as indicated by an inability to disperse these at 0 degrees C. Following 24 h of incubation at 37 degrees C, the DOPA-collagen gels were insoluble in dilute acetic acid even under denaturing conditions. The effect on both gel stability and solubility was concentration-dependent and was maximum at 1 x 10(-3)M. Gel solubility changes were significant, with the greatest change occurring between concentrations of 3.1 x 10(-5)M and 1.65 x 10(-5)M. DOPA exposure did not alter the fibrillar banding pattern seen at the electron microscopic level. Collagen felts prepared by lyophilization of DOPA-collagen gels demonstrated an increase in shrinkage temperature which after 24 h exceeded that of rat tail tendon. Preformed collagen felts incubated for 24 h in the presence of 1 mM DOPA also had a greatly increased shrinkage temperature. Pepsin-treated collagen control felts were altered with respect to control felts in a time dependent manner. The wet tensile strength increased to four times that of control after 3 days of incubation at 37 degrees C. Matrix extensibility initially increased to 1.5 times that of control felts after 4 days of incubation at 37 degrees C, but decreased to below control values following 6 additional days of incubation. These properties suggest that DOPA may be useful as a stabilizing agent of collagen biomedical prostheses.
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PMID:The stabilization of fibrillar collagen matrices with 3,4-dihydroxyphenylalanine. 191 1

The digital flexor tendons of the neonate and adult horse have been compared with respect to variation in extracellular matrix composition along their length. Two pepsin-sensitive, acetic acid soluble proteins, molecular weight (Mr) 52 kD (np 52) and Mr 54 kD (np 54), were prominent throughout the length of neonatal tendons. In adult tendon, np 52 and np 54 were less abundant and restricted to the cannon (metacarpal) region. In contrast, a single pepsin- and collagenase-resistant protein of Mr 55 kD (fp 55) was exclusive to the fetlock (metacarpophalangeal joint) region regardless of age, although more distinct in the adult. Pepsin extracted fp 55 precipitated at 2.0 M sodium chloride: 0.5 M acetic acid and was further purified to homogeneity by bacterial collagenase digestion. Analysis of fp 55 amino acid composition revealed the presence of a large proportion of glycine residues (379 of 1001), suggesting a possible homology with the collagen family. These data demonstrate that the composition of equine digital flexor tendons varies with age, is heterogeneous along its length, and suggests that variation in tendon extracellular matrix composition is influenced by functional requirements.
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PMID:Age- and position-related heterogeneity of equine tendon extracellular matrix composition. 211 5

Microdissection of acellular rat renal cortex with pepsin was carried out to investigate the morphological substructure of glomerular basement membrane (GBM) by high resolution SEM. Renal cortical blocks (less than 5 mm3) from adult male Sprague Dawley rats were rendered acellular by sequential detergent extraction and digested up to 184 hrs with 5 mg/ml pepsin (185 U/mg) in 0.5 M acetic acid (pH 2) at 10-15 degrees C. Samples were conventionally prepared for SEM, and observed at original magnifications of 500-100,000 diameters. At low magnifications (500-5,000x), acellular GBM surfaces appeared smooth at all digestion times. At higher magnifications (50,000-100,000x), control GBM surfaces were finely granular. Granule diameter ranged from 20-80 nm, with most between 30-40 nm. Pepsin digestion did not affect average granule size. Beginning at 44 hrs of digestion, intrinsic fibrillar structures comprised of linear arrays of 20-40 nm granules were observed on/in GBM surfaces. At later incubation times, this component of GBM became more extensive. At 160 hrs, the fibrillar arrays frequently bifurcated and showed distinctive "forked" termini, some of which comprised two sides of a triangle (120-150 nm on a side). Fork "handles" (310-350 nm in length) radiated from each angle of the triangle. These sometimes terminated in large granules (approximately 100 nm in diameter), two of which appeared to connect fibrillar arrays end-to-end. Together with other arrays, the interconnected triangles appeared to comprise a three-dimensional meshwork extending into the GBM and possibly providing support for, its granular components.
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PMID:High resolution SEM analysis of acellular glomerular basement membrane following pepsin digestion: intrinsic fibrillar structures. 213 83

A procollagen in the soluble fraction of rabbit vitreous was isolated by dialysis against dilute acetic acid and partially purified by Bio-Gel A 5M gel filtration. The molecule was identified to be type II procollagen by comparing its segment-long-spacing (SLS) banding pattern with that of standard type II collagen isolated from rabbit articular cartilage. Electron microscopy of the SLS of this type II procollagen revealed a fuzzy propeptide extension at the N-terminal end of the molecule. Pepsin digestion of the procollagen removed this extension, thus converting the molecule into a collagen which had mobility similar to that of pepsin-soluble cartilage type II collagen in SDS-polyacrylamide gel electrophoresis. No inter-chain disulfide bond was found in the propeptide extension when the procollagen samples were electrophoresized with or without mercaptoethanol. Comparison of the cyanogen bromide peptide map of the type II procollagen with that of the pepsin-soluble type II collagen indicated that two extra peptides were present in the digest of procollagen. All of this evidence suggested that the procollagen in the soluble vitreous body of the rabbit eye was a novel type II procollagen with a propeptide extension only at the N-terminus.
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PMID:Identification of type II procollagen in rabbit vitreous. 401 Nov 29

1. The abomasum of the milk-fed calf has been examined using an adaptation of the Serial Test Meal method devised by Hunt & Spurrell (1951). The emptying process, acid secretion and pepsin secretion were studied.2. Using serial test meals of simple solutions instilled into the abomasum via a cannula, our investigation leaves no doubt that the osmolarity of the abomasal contents significantly modifies the rate of abomasal emptying.3. Hypotonic and isotonic solutions of sodium chloride and sodium bicarbonate increase abomasal emptying but bicarbonate is most effective.4. Increasing the concentration of solutes in the abomasal contents slows abomasal emptying. Sodium chloride, sodium bicarbonate, ammonium chloride and urea do not delay abomasal emptying until hypertonic concentrations are attained. Hypotonic solutions of potassium chloride, calcium chloride, glucose, lactose, hydrochloric acid and acetic acid delay abomasal emptying.5. The results obtained in the calf show that the abomasum is under restraint probably from duodenal receptors as is the simple stomach (Hunt & Knox, 1968) and that an osmoreceptor as postulated by Hunt (1956) is an important factor in this mechanism.6. Acid secretion is inhibited when hypertonic solutions are instilled into the abomasum.7. Pepsin secretion is not affected by simple solutions in the abomasum.8. Gastric function in the milk-fed calf appears to be controlled by mechanisms essentially similar to those already demonstrated in the simple stomach.
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PMID:The effect of some molecules and ions on gastric function in the milk-fed calf. 456 11

1. Collagen was extracted from chick skin with dilute acetic acid followed by dilute acetic acid containing pepsin. 2. The solubilized collagens were purified and portions subjected to further digestion by pepsin. 3. This treatment decreased the aldehyde content but contamination by hexosamine was not diminished. 4. Pepsin treatment converted practically all the acid-soluble collagen into monomeric subunits (alpha-chains), but the pepsinsolubilized material retained a significant amount of higher subunits (beta- and gamma-chains). 5. Treatment lowered the rate of fibrillogenesis by acid-soluble collagen, but was without effect on pepsin-solubilized collagen.
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PMID:Pepsin treatment of avian skin collagen. Effects on solubility, subunit composition and aggregation properties. 457 95


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