The extent of N epsilon-(carboxymethyl)lysine formation in lens proteins and polylysine by the autoxidation products of ascorbic acid.
The extent of N epsilon-(carboxymethyl)lysine formation in lens proteins and polylysine by the autoxidation products of ascorbic acid.
复制标题
抗坏血酸的自氧化产物在晶状体蛋白和聚赖氨酸中形成 N ε-(羧甲基)赖氨酸的程度。
DOI：
10.1016/0304-4165(92)90080-e
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Ortwerth,BJ
中科院分区：
文献类型：
--
作者：
Slight,SH;Prabhakaram,M;Shin,DB;Feather,MS;Ortwerth,BJ
抗坏血酸（阿萨）的自氧化作用导致形成能够在体外糖化和交联蛋白质的化合物。当牛透镜的可溶性晶状体蛋白与阿萨在氰基硼氢化钠存在下孵育时，观察到单一的主要加合物，其外观与赖氨酸的损失相关。当聚赖氨酸与等量的阿萨在相同条件下反应时，在37°C下孵育四周后，该产物占总赖氨酸含量的一半。通过TLC、GC/MS和氨基酸分析，确定了该加合物为N-羧甲基赖氨酸（CML）。在氰基硼氢化钠存在下，阿萨的几种氧化产物各自与聚赖氨酸反应，以鉴定反应性物质。CML是与阿萨和脱氢抗坏血酸（DHA）形成的主要加合物。在1 - 2，3-二酮古洛糖酸（DKG）和l-苏糖中观察到显著减少的量，而在l-苏-戊糖-2-酮糖（l-木酮糖）中未形成CML。在不存在氰基硼氢化钠的情况下，CML的产率与每种阿萨自氧化产物和所需氧相似。与[1- 14 C]阿萨的反应导致[14 C]CML，但仅在NaCNBH 3存在的情况下。至少有两种CML形成的途径似乎取决于NaCNBH 3是否存在以减少赖氨酸和DHA之间形成的推定席夫碱。
The autoxidation of ascorbic acid (ASA) leads to the formation of compounds which are capable of glycating and crosslinking proteind in vitro. When the soluble crystallins from bovine lens were incubated with ASA in the presence of sodium cyanoborohydride, a single major adduct was observed, whose appearance correlated with the loss of lysine. When polylysine was reacted with equivalent amounts of ASA under the same conditions, this product represented half of the total lysine content after four weeks of incubation at 37°C. This adduct was isolated and identified asNϵ-(carboxymethyl)lysine (CML) by TLC, GC/MS and amino acid analysis. Several oxidation products of ASA were each reacted with polylysine in the presence of sodium cyanoborohydride to identify the reactive spcies. CML was the major adduct formed with either ASA and dehydroascorbic acid (DHA). Markedly diminished amounts were seen withl-2,3-diketogulonic acid (DKG), andl-threose, while no CML was formed withl-threo-pentos-2-ulose (l-xylosone). In the absence of sodium cyanoborohydride the yield of CML was similar with each of the ASA autoxidation products and required oxygen. Reactions with [1-14C]ASA gave rise to [14C]CML, but only with NaCNBH3present. At least two routes of CML formation appear to be operating depending upon whether NaCNBH3is present to reduce the putative Schiff base formed between lysine and DHA.