ALDOSE REDUCTASE AND DIABETIC COMPLICATIONS

一些糖尿病并发症，如白内障，视网膜病变， 神经病变和肾病在患有神经病变的人中是常见的。 糖尿病一段时间。 山梨醇的积累，由于其 通过透镜中生物膜的相对不渗透性，神经 组织和血管可能是这些并发症的原因。的 这些并发症的主要原因可能是渗透压失衡， 山梨醇（一种相对不渗透多元醇）的积累 通过生物膜进入组织。 渗透压不平衡 导致水合作用增加、膜拉伸和功能障碍。 醛糖 还原酶在NADPH的介导下将糖还原为多元醇。 这 酶可能与糖性白内障有关，因为 醛糖还原酶抑制剂如sorbinil和alrestatin， 动物预防或显著延迟白内障发生。 我们发现 来自不同组织醛糖还原酶可以被激活数倍 葡萄糖-6-磷酸、葡萄糖和NADPH各10 μ M。 的 未活化的酶被15 μ M ADP、2，3-DPG或 3PGA。 激活的酶不受这些磷酸化的 糖酵解中间体，并且对sorbinil的抑制更有抗性 而不是未活化的酶。 的动力学性质 从糖尿病患者的组织中纯化的醛糖还原酶 从实验诱导的糖尿病和半乳糖血症的动物 将被研究并与血糖和多元醇水平相关联。 的 醛酮还原酶将从人组织中纯化至均一， 将研究它们的动力学、结构和免疫学性质。 我们从人红细胞中纯化了醛糖还原酶， 并且已经证明，在糖尿病患者中， 随着血糖的升高而升高。 随着血糖水平的升高 超过200 mg %，所有酶保持活化形式。 葡萄糖 葡萄糖-6-P可能与醛糖还原酶共价结合， 这些代谢物激活/灭活酶的机制是 不知道。 所有抑制剂的结合特性和 因此，将研究酶活化的机制。 肽图谱， 结合处肽的N-末端、C-末端氨基酸序列 中心将确定。 这些研究将有助于了解 醛糖还原酶在糖尿病并发症病理生理学中的作用 并最终帮助研究人员设计出特定的抑制剂 醛糖还原酶

Some of the diabetic complications such as cataractogenesis, retinopathy, neuropathy, and nephropathy are common among the persons suffering from diabetes for a period of time. Accumulation of sorbitol, due to its relative impermeability through biological membranes in the lens, neural tissues, and blood vessels may be the cause of these complications. The major cause of these complications could be the osmotic imbalance due to the accumulation of sorbitol, a polyol which is relatively impermeable through biological membranes, in the tissues. The osmotic imbalance will lead to increased hydration, membrane stretch, and dysfunction. Aldose reductase reduces sugars to polyols with the mediation of NADPH. This enzyme is probable involved in sugar cataracts, because administration of aldose reductase inhibitors such as sorbinil and alrestatin to experimental animals prevents or significantly delays cataractogenesis. We have found that aldose reductase from different tissues can be activated several fold by 10 Mu M each of glucose-6-phosphate, glucose, and NADPH. The unactivated enzyme is irreversibly inhibited by 15 Mu M ADP, 2,3-DPG, or 3PGA. The activated enzyme is not inhibited by these phosphorylated glycolytic intermediates and is more resistant to inhibition by sorbinil and alrestatin than is the unactivated enzyme. The kinetic properties of aldose reductase purified from the tissues of the diabetic subjects as well as from the animals with experimentally induced diabetes and galactosemia will be studied and correlated with blood sugar and polyol levels. The aldo-keto reductases will be purified to homogeneity from human tissues and their kinetic, structural, and immunological properties will be studied. We have purified aldose reductase from human erythrocytes to homogeneity and have demonstrated that in diabetic subjects the enzyme activity increases with increase in blood sugar. With blood glucose levels higher than 200 mg percent, all the enzyme remains in the activated form. Glucose and glucose-6-P probably covalently bind to aldose reductase but the mechanism of activation/inactivation of the enzyme by these metabolites is not known. The binding characteristics of all the inhibitors and the mechanism of enzyme activation will therefore be studied. Peptide mapping, N-terminal, C-terminal, amino acid sequence of the peptides at the binding centers will be determined. These studies will help in understanding the role of aldose reductase in the pathophysiology of diabetic complications and should eventually aid the investigators in devising specific inhibitors of aldose reductase.