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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Absorbable corneal sutures of PGA monofilaments were tested in rabbit eyes. Compared to chromic collagen 8/0 the sutures were tolerated well, but the absorption time of 14.6 days is considered as being too short for corneal surgery.
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PMID:Absorption time of PGA monofilaments and collagen 8/0 in corneal sutures. 79 Sep 12

Pepsin solubilization of small and large noduled liver cirrhosis yielded two types of collagen (precipitated at 1.7 and 2.5 M NaCl concentrations) as demonstrated by electronmicroscopy. The 1.7 M NaCl precipitate was identified as type III collagen using an immunofluorescence technique. The 2.5 M NaCl precipitate appeared to be type I in the electronmicroscope. However, immunofluorescent and biochemical studies indicated that it was not type I but a type of collagen not yet described.
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PMID:Liver cirrhosis: immunofluorescence and biochemical studies demonstrate two types of collagen. 109 5

Anchorin CII is a collagen binding protein of the annexin family associated with plasma membranes of chondrocytes, osteoblasts, and many other cells. As a major constituent of cartilage-derived matrix vesicles it has been shown to bind to native type II and X collagen. In accordance with this observation, here we show the localization of anchorin CII in the extracellular matrix of calcifying cartilage in the fetal human growth plate, and that it was restricted to the chondrocyte surface in proliferating and resting cartilage. Furthermore, we present evidence, using a slot blot assay, that anchorin CII not only binds to native type II and X collagen, but also to chondrocalcin, the carboxy-terminal extension of type II procollagen, in a calcium-independent manner. Pepsin digestion of type II collagen results in loss of anchorin CII binding, confirming our previous notion that the telopeptide region of type II collagen carries anchorin CII binding sites.
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PMID:Selective binding of anchorin CII (annexin V) to type II and X collagen and to chondrocalcin (C-propeptide of type II collagen). Implications for anchoring function between matrix vesicles and matrix proteins. 139 63

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

We have shown that thrombospondin (tsp), like fibronectin (fn) and von Willebrand factor (vWf), exhibits a rapid, specific and saturable binding to collagen type I fibres (from bovine tendon). The level of binding at saturation is very similar to that of vWf. As with fn and vWf, the interaction is ionic in character and appears to occur by a polyvalent mechanism since there is little inhibition of interaction by monomeric collagen. The conformation of tsp, like that of fn and vWf, is important since denaturation causes reduced complexing. Furthermore, conformational changes in tsp due to the presence of Ca++ can modulate the amount of complex formed under physiological conditions. Tsp, like vWf but in contrast to fn, shows little affinity for denatured fibres emphasizing the importance of collagen conformation. Pepsin digestion suggests an important role for collagen telopeptides; vWf- and fn-binding sites are located more within the collagen triple helix. Comparison of the effect on binding after leucine aminopeptidase or carboxypeptidase digestion suggests involvement of the N- rather than C-terminal telopeptides. No evidence was found for a role for fn, the proteoglycan PG2 or collagen type V, which could be present in type I fibres, in mediating the interaction between tsp and the fibres. VWf did not inhibit the interaction of tsp, but fn did slightly when tested in large excess. This suggests separate binding sites in collagen for all three ligands since fn and vWf are also known to bind independently of each other.
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PMID:Characterization of thrombospondin binding to collagen (type I) fibres: role of collagen telopeptides. 187 Apr 47

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 biosynthesis of type I, type V and type VI collagens was studied by incubation of calf corneas in vitro with [3H]proline as a marker. Pepsin-solubilized collagen types were isolated by salt fractionation and quantified by SDS/PAGE. Expressed as proportions of the total hydroxyproline solubilized, corneal stroma comprised 75% type I, 8% type V and 17% type VI collagen. The rates of [3H]proline incorporation, linear up to 24 h for each collagen type, were highest for type VI collagen and lowest for type I collagen. From pulse-chase experiments, the calculated apparent half-lives for types I, V and VI collagens were 36 h, 10 h and 6 h respectively.
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PMID:Relative rates of biosynthesis of collagen type I, type V and type VI in calf cornea. 200 24

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

Type X collagen was extracted with 1 M-NaCl and 10 mM-dithiothreitol at neutral pH from fetal-bovine growth cartilage and purified to homogeneity by using f.p.l.c. gel filtration on a Superose 12 column, followed by ion-exchange chromatography on a Mono Q column. The purified protein migrates in SDS/polyacrylamide gels with an apparent Mr of 58,000 under reducing conditions and as a high-Mr oligomer in its unreduced form. The amino acid composition is similar to the published composition of chick type X collagen. Pepsin digestion at 4 degrees C decreases the Mr of the monomer to 43,000; purified bacterial collagenase digests most of the molecule, leaving a non-collagenous domain of apparent Mr 15,000, which probably represents the C-terminal globular domain. The IgG fraction from a rabbit antiserum raised against purified bovine type X collagen was specific for this collagen by the criteria of e.l.i.s.a. and immunoblotting after immunoabsorption with collagen types I, II, IX and XI. Immunofluorescence localization of type X collagen in sections of fetal-bovine and human cartilage was possible after acetone fixation of sections and hyaluronidase treatment. Type X collagen was restricted to the zone of hypertrophic and calcified cartilage inside the bone spicules of the growth plate.
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PMID:Isolation of bovine type X collagen and immunolocalization in growth-plate cartilage. 240 43


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