CHEMICAL ASPECTS OF NONENZYMIC GLYCOSYLATION OF PROTEINS

非酶糖基化--一种蛋白质翻译后修饰 反应，简单地反映了‘醛’的潜力 醛糖与氨基形成可逆席夫碱加合物的作用 函数及其后续的分子内重排 重排，形成更稳定的酮胺加合物。活体内 非酶糖基化可以被认为是连续的、累积的 对人体蛋白质和可能的核酸的化学侮辱 磷脂。组织蛋白的葡萄糖依赖的交联性，以及 糖尿病的加速衰老已被描述为其后果 增强了身体蛋白质的非酶糖化作用。少校 本提案的目标是：a)了解立体化学 易感Epsilon-氨基附近的蛋白质特征 促进Amadori重排的小组(S)和b)确定 酮胺键的羰基功能对苯环的反应性 了解蛋白质的游离氨基是否依赖于葡萄糖 非酶糖化蛋白的交联反应是一种 化学反应这种反应的化学结果。模型四肽，含有 体内的赖氨酸残基将被合成，而 邻位氨基酸残基对大豆蛋白非酶糖化速率的影响 他们的Epsilon-氨基将被调查。一个相对简单的 非酶糖基化体外模型蛋白质系统的开发 使用核糖核酸酶-A。酮胺的羰基功能的反应性 与丹西肼和还原胺化的联系 将对丹磺酰乙二胺进行调查。我们将尝试 开发这些反应以用于定量的新荧光分析 估计非酶糖基化。羰基的反应性 酮胺与蛋白质氨基形成稳定的功能 将对荧光产品进行调查。荧光/交叉线 产物将通过完全的酶消化的RPHPLC分离 交联型核糖核酸酶-A并进行了表征。结晶素的荧光加合物 胶原蛋白将通过类似的程序分离出来，以建立其 与合成材料的同一性。这些研究的结果将 增加我们对非酶化学方面的基本知识 蛋白质的糖基化及其化学后果，从而其 在糖尿病和衰老过程中的病理生理贡献。

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.