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KMID : 1134819990280061332
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Journal of the Korean Society of Food Science and Nutrition
1999 Volume.28 No. 6 p.1332 ~ p.1338
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The Effect of L - Ascorbic Acid on the Formation of Immature Crosslink in Bone Collagen in vitro
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Kim Mi-Hyang
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Abstract
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Intermolecular collagen cross-links stabilize collagen fibrils and are necessary for normal tensile strength in collagen fibrils. Once the fibrils are aligned, hydroxyllysine, hydroxylysine-derived aldehyde modified enzymatically, reacts with hydroxylysine to form the dehydrodihydroxylysinonorleucine (DHLNL), an immature crosslink. pyridinoline, one of matured cross-links is presumably formed nonenzymatically through condensation of DHLNL and hydroxylysine residue. It is widely distributed in hard connective tissues such as cartilage, bone and tendon. L-ascorbic acid(AsA) is well known to be required for the enzymatic hydroxylation of proline and lysine in collagen fibrils. The purpose of this study is to clarify the role of AsA on the biosynthesis of DHLNL in vitro. We examined the effect of AsA on the formation of hydroxylysine and DHLNL in collagen. Pyridinoline and DHLNL were measured as a function of time. The contents of DHLNL was increased, reached maximum within 2 hr and was held until 24 hr, then it decreased slowly. On the contrary, pyridinoline increased gradually after 24 hr and continued to increase for 2 weeks. Moreover, the contents of DHLNL remarkably decreased at 60 min after incubation, the contents of DHLNL was decreased by addition of AsA or dehydroascorbic acid(DHA). These results suggest that the supplementation of AsA causes decrease in DHLNL formation and pyridinoline formed by nonenzymatic reaction of DHLNL.
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KEYWORD
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collagen, pyridinoline, lysyl oxidase, hydroxylysine, immature crosslink, dehydrodihydroxylysinonorleucine
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