Yamauchi M, Chandler G S, Tanzawa H, Katz E P
Dental Research Center, University of North Carolina, Chapel Hill 27599-7455, USA.
Biochem Biophys Res Commun. 1996 Feb 15;219(2):311-5. doi: 10.1006/bbrc.1996.0229.
We have quantitatively characterized, for the first time, the cross-linking in bovine cornea collagen as a function of age. The major iminium reducible cross-links were dehydro-hydroxylysinonorleucine (deH-HLNL) and dehydro-histidinohydroxymerodesmosine (deH-HHMD). The former rapidly diminished after birth; however, the latter persisted in mature animals at a level of 0.3 - 0.4 moles/mole of collagen. A nonreducible cross-link, histidinohydroxylysinonorleucine (HHL), previously found only in skin, was also found to be a major mature cross-link in cornea. The presence of HHL indicates that cornea fibrils have a molecular packing similar to skin collagen. However, like deH-HHMD, the HHL content in corneal fibrils only reaches a maximum value with time about half that of skin. These data suggest that the corneal fibrils are comprised of discrete filaments that are internally stabilized by HHL and deH-HHMD cross-links. This pattern of intermolecular cross-linking would facilitate the special collagen swelling property required for corneal transparency.
我们首次定量表征了牛角膜胶原蛋白中的交联随年龄的变化情况。主要的可被亚胺还原的交联键是脱氢羟赖氨酰正亮氨酸（deH-HLNL）和脱氢组氨酰羟赖氨酰半胱氨酸（deH-HHMD）。前者在出生后迅速减少；然而，后者在成熟动物中以每摩尔胶原蛋白0.3 - 0.4摩尔的水平持续存在。一种以前仅在皮肤中发现的不可还原交联键，组氨酰羟赖氨酰正亮氨酸（HHL），也被发现是角膜中的主要成熟交联键。HHL的存在表明角膜纤维具有与皮肤胶原蛋白相似的分子堆积。然而，与deH-HHMD一样，角膜纤维中的HHL含量随时间达到的最大值约为皮肤的一半。这些数据表明角膜纤维由离散的细丝组成，这些细丝通过HHL和deH-HHMD交联在内部得到稳定。这种分子间交联模式将有助于角膜透明所需的特殊胶原蛋白膨胀特性。
