Dunn J A, McCance D R, Thorpe S R, Lyons T J, Baynes J W
Department of Chemistry, University of South Carolina, Columbia 29208.
Biochemistry. 1991 Feb 5;30(5):1205-10. doi: 10.1021/bi00219a007.
N epsilon-(Carboxymethyl)lysine (CML) is formed on oxidative cleavage of carbohydrate adducts to lysine residues in glycated proteins in vitro [Ahmed et al. (1988) J. Biol. Chem. 263, 8816-8821; Dunn et al. (1990) Biochemistry 29, 10964-10970]. We have shown that, in human lens proteins in vivo, the concentration of fructose-lysine (FL), the Amadori adduct of glucose to lysine, is constant with age, while the concentration of the oxidation product, CML, increases significantly with age [Dunn et al. (1989) Biochemistry 28, 9464-9468]. In this work we extend our studies to the analysis of human skin collagen. The extent of glycation of insoluble skin collagen was greater than that of lens proteins (4-6 mmol of FL/mol of lysine in collagen versus 1-2 mmol of FL/mol of lysine in lens proteins), consistent with the lower concentration of glucose in lens, compared to plasma. In contrast to lens, there was a slight but significant age-dependent increase in glycation of skin collagen, 33% between ages 20 and 80. As in lens protein, CML, present at only trace levels in neonatal collagen, increased significantly with age, although the amount of CML in collagen at 80 years of age, approximately 1.5 mmol of CML/mol of lysine, was less than that found in lens protein, approximately 7 mmol of CML/mol of lysine. The concentration of N epsilon-(carboxymethyl)hydroxylysine (CMhL), the product of oxidation of glycated hydroxylysine, also increased with age in collagen, in parallel with the increase in CML, from trace levels at infancy to approximately 5 mmol of CMhL/mol of hydroxylysine at age 80.(ABSTRACT TRUNCATED AT 250 WORDS)
N-ε-（羧甲基）赖氨酸（CML）是在体外糖基化蛋白质中碳水化合物加合物与赖氨酸残基发生氧化裂解时形成的[艾哈迈德等人（1988年）《生物化学杂志》263卷，8816 - 8821页；邓恩等人（1990年）《生物化学》29卷，10964 - 10970页]。我们已经表明，在人体晶状体蛋白中，果糖赖氨酸（FL，葡萄糖与赖氨酸的阿马多里加合物）的浓度随年龄保持恒定，而氧化产物CML的浓度则随年龄显著增加[邓恩等人（1989年）《生物化学》28卷，9464 - 9468页]。在这项工作中，我们将研究扩展至对人体皮肤胶原蛋白的分析。不溶性皮肤胶原蛋白的糖基化程度高于晶状体蛋白（胶原蛋白中FL为4 - 6 mmol/摩尔赖氨酸，而晶状体蛋白中为1 - 2 mmol/摩尔赖氨酸），这与晶状体中葡萄糖浓度低于血浆浓度一致。与晶状体不同，皮肤胶原蛋白的糖基化有轻微但显著的年龄依赖性增加，20岁至80岁之间增加了33%。与晶状体蛋白一样，新生儿胶原蛋白中仅以痕量水平存在的CML随年龄显著增加，尽管80岁时胶原蛋白中CML的量约为1.5 mmol/摩尔赖氨酸，低于晶状体蛋白中的量，约为7 mmol/摩尔赖氨酸。糖基化羟赖氨酸氧化产物N-ε-（羧甲基）羟赖氨酸（CMhL）的浓度在胶原蛋白中也随年龄增加，与CML的增加平行，从婴儿期的痕量水平增加到80岁时约5 mmol/摩尔羟赖氨酸。（摘要截取自250字）
