CHEMICAL ASPECTS OF NONENZYMIC GLYCOSYLATION OF PROTEINS

非酶糖基化，一种翻译后蛋白质修饰 反应，只是反映了潜在的'反作用' 醛糖与氨基形成可逆席夫碱加合物的功能 功能和子序列分子内重排，阿马多里 重排，以形成更稳定的酮胺加合物。 体内 非酶糖基化可以被认为是一种连续的、累积的 对身体蛋白质和可能的核酸的化学伤害， 磷脂 组织蛋白的葡萄糖依赖性交联，以及 糖尿病的加速衰老，已经被描述为， 增强身体蛋白质的非酶糖基化。 主要 本提案的目标是a）理解立体化学 在敏感ε-氨基附近的蛋白质的特征 促进Amadori重排的基团，和B）确定 酮胺键的羰基官能团对 蛋白质的游离氨基，以了解葡萄糖依赖性 与非酶葡糖基化蛋白质的交联反应是一种 这种反应性的化学后果。 模型四肽 将合成内部赖氨酸残基，并且 相邻氨基酸残基对非酶葡萄糖基化速率的影响 将研究它们的ε-氨基。 一个相对简单的 建立了体外非酶糖基化模型蛋白体系 使用核糖核酸酶-A。 酮胺羰基官能团的反应性 与丹磺酰肼的连接以及与 将研究丹磺酰乙二胺。 将试图 开发这些反应用于定量的新荧光测定， 估计非酶葡糖基化。 羰基的反应性 酮胺的功能与蛋白质的氨基形成稳定的 将研究荧光产品。 荧光/交联 将通过RPHPLC完全酶消化分离产物， 交联RNase-A并表征。 水晶蛋白荧光加合物 和胶原蛋白将通过类似的程序分离，以建立它们的 与合成材料相同。 这些研究的结果将 增加我们对非酶的化学方面的基本知识 蛋白质的葡萄糖基化和化学后果，因此其 在糖尿病和衰老过程的病理生理学方面的贡献。

Nonenzymic glycosylation, a post-translational protein modification reaction, is simply a reflection of the potential of the 'aldehydic' function of aldoses to form a reversible Schiff-base adduct with the amino functions and the subsequence intramolecular rearrangement, Amadori rearrangement, to form a more stable ketoamine adducts. The in vivo nonenzymic glycosylation can be considered as a continuous, cumulative chemical insult to body proteins and possibly nucleic acids and phospholipids. The glucose dependent cross-linking of tissue proteins, and the accelerated aging in diabetes, has been described, as the consequence of enhanced nonenzymic glucosylation of body proteins. The major objectives of the present proposal are a) to understand the stereochemical features of the protein in the vicinity of the susceptible Epsilon-amino group(s) that facilitate the Amadori rearrangement and b) to determine the reactivity of the carbonyl function of the ketoamine linkages towards the free amino groups of proteins to understand whether the glucose-dependent cross-linking reaction seen with nonenzymically glucosylated protein is a chemical consequence of such a reactivity. Model tetrapeptides containing an internal lysine residue will be synthesised, and the influence of the neighboring amino acid residues on the rate of nonenzymic glucosylation of their Epsilon-amino group will be investigated. A relatively simple in vitro model protein system of nonenzymic glucosylation will be developed using Ribonuclease-A. Reactivity of the carbonyl function of the ketoamine linkages towards dansylhydrazine and also for reductive amination with dansyl ethylenediamine will be investigated. Attempts will be made to develop these reactions for a quantitative new fluorescent assay to estimate nonenzymic glucosylation. The reactivity of the carbonyl functions of ketoamines with the amino groups of proteins to form stable fluorescent products will be investigated. Fluorescent/cross-lined products will be isolated by RPHPLC of a complete enzymatic digest of cross-linked RNase-A and characterized. Fluorescent adduct from crytallin and collagen will be isolated by similar procedures to establish their identity with the synthetic material. The results of these studies will increase our basic knowledge about the chemical aspects of nonenzymic glucosylation of proteins and the chemical consequences, and thus its contribution in the pathophysiology of diabetes mellitus and aging process.