Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.36 (hyaluronidase)
 4,606 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Matrix vesicles (MV) were shown to initiate mineralization in cartilage and other vertebrate tissues. However, the factors that drive this process remain to be fully elucidated. Recent studies have shown that a preformed nucleational core consisting mainly of a Ca(2+)-phosphatidylserine-Pi complex, is necessary for the accumulation of Ca2+ by MV. In addition, the collagens attached to the MV surface were shown to play an important role in stimulating Ca2+ uptake. In this study, we extend this knowledge by showing that both, the nucleational core and the collagens (types II and X), are co-requirements for rapid influx of Ca2+ into intact MV. MV to which collagen fragments were attached were released from hypertrophic chicken cartilage by trypsin and collagenase digestion (trypsin/collagenase-released MV (TCRMV), while "collagen-free" MV were released by hyaluronidase and collagenase digestion (hyaluronidase/collagenase-released MV (HCRMV). In contrast to TCRMV which showed active uptake of Ca2+, HCRMV showed only little uptake. However, binding of native type II collagen to HCRMV stimulated uptake of Ca2+. Sucrose gradients separated TCRMV and HCRMV into three different density fractions: a low density top fraction (SI), an intermediate density middle fraction (SII), and a high density pellet fraction (SIII). The SIII fractions of TCRMV and HCRMV contained significantly higher levels of mineral ions than did the SI and SII fractions. Only the SIII fraction of TCRMV which contained a stable nucleational core and surface-attached collagens, showed active Ca2+ uptake; all other sucrose fractions of TCRMV and HCRMV showed little or no uptake. Detergent treatment to purposely rupture the membrane greatly enhanced Ca2+ uptake by the SIII fraction of HCRMV, presumably by exposing the internal nucleational core. Addition of either native type II or type X collagen to the intact SIII fraction of HCRMV stimulated Ca2+ uptake to a level similar to that of the SIII fraction of TCRMV; however, incubation of the SI and SII fractions of either TCRMV or HCRMV with type II or X collagen did not activate Ca2+ uptake. These findings indicate that both a functional nucleational core and surface-attached collagens need to be present to support active mineralization of MV.
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PMID:Roles of the nucleational core complex and collagens (types II and X) in calcification of growth plate cartilage matrix vesicles. 805 Oct 98

Type X collagen is a short-chain collagen that is strongly expressed in hypertrophic chondrocytes. In this study, we used an immunohistochemical technique exploiting a prolonged hyaluronidase unmasking of type X collagen epitopes to show that type X collagen is not restricted to calcified cartilage, but is also present in normal canine noncalcified articular cartilage. A 30 degrees valgus angulation procedure of the right tibia was performed in 15 dogs at the age of 3 months, whereas their nonoperated sister dogs served as controls. Samples were collected 7 and 18 months after the surgery and immunostained for type X collagen. The deposition of type X collagen increased during maturation from age 43 weeks to 91 weeks. In the patella, most of the noncalcified cartilage stained for type X collagen, whereas, in the patellar surface of the femur, it was present mainly in the femoral groove close to cartilage surface. In femoral condyles, the staining localized mostly in the superficial cartilage on the lateral and medial sides, but not in the central weight-bearing area. In tibial condyles, type X collagen was often observed close to the cartilage surface in medial parts of the condyles, although staining could also be seen in the deep zone of the cartilage. Staining for type X collagen appeared strongest at sites where the birefringence of polarized light was lowest, suggesting a colocalization of type X collagen with the collagen fibril arcades in the intermediate zone. No significant difference in type X collagen immunostaining was observed in lesion-free articular cartilage between controls and dogs that underwent a 30 degrees valgus osteotomy. In osteoarthritic lesions, however, there was strong immunostaining for both type X collagen and collagenase-induced collagen cleavage products. The presence of type X collagen in the transitional zone of cartilage in the patella, femoropatellar groove, and in tibial cartilage uncovered by menisci suggests that it may involve a modification of collagen fibril arrangement at the site of collagen fibril arcades, perhaps providing additional support to the collagen network.
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PMID:Site-specific immunostaining for type X collagen in noncalcified articular cartilage of canine stifle knee joint. 1253 63