SYNTHESIS AND BIOCHEMISTRY OF ASCORBIC ACID ANALOGUES

抗坏血酸（维生素C）， 人类健康，是几种酶促作用的电子供体， 作为一种抗氧化剂，并参与宿主防御 机制、内分泌功能和视觉过程（透镜）。 最近对抗坏血酸生物化学的重新关注， 由于认识到相对而言 关于维生素的浓度所需的最佳 发挥这几个作用。在酶的情况下， 反应，过程的最佳速率被定义为该浓度 使反应达到Vmax而没有毒性。的一部分 一个程序，以确定这些浓度，在原位动力学 已经对某些维生素C相关的 反应.除了检查维生素C的功能作用外， C，最近对有效运输机制的表征， 维生素C跨细胞膜转运强调了 维生素对生物过程的重要性。我们有 合成的放射性标记的6-脱氧-6-碘抗坏血酸作为工具， 研究抗坏血酸转运系统的其他细节。 运输研究表明，这将是一个有用的工具， 分离抗坏血酸转运蛋白。探讨 2-羟基对抗坏血酸活性的重要性，我们 预先制备的2-脱氧-抗坏血酸和2-脱氧-2-卤代 抗坏血酸，包括2-脱氧-2-氟抗坏血酸，电子等排的 和等极性的、不可氧化的类似物。环状半缩酮形式 还制备了2，2-二氟-2-脱氧抗坏血酸，其结构为 其对应于脱氢抗坏血酸的环状半缩酮形式 酸这些类似物的传输特性，以及它们的 对谷氨酰氧还蛋白的影响， 抗坏血酸，正在研究中。

Ascorbic acid (vitamin C), a dietary requirement for human health, is an electron donor for several enzymatic actions, functions as an antioxidant, and is implicated in host defense mechanisms, endocrine function and the visual process (lens). Recent renewed interest in the biochemistry of ascorbic acid has been prompted by the realization that relatively little is known concerning the concentrations of the vitamin required for optimum functioning of these several roles. In the case of enzymatic reactions, optimal rate of a process is defined as that concentration that allows the reaction to reach Vmax without toxicity. As part of a program to determine these concentrations, in situ kinetic measurements have been carried out for certain vitamin C-linked reactions. In addition to examination of functional roles of vitamin C, recent characterization of efficient transport mechanisms that translocate vitamin C across cellular membranes has emphasized the importance of the vitamin to biological processes. We have synthesized radiolabelled 6-deoxy-6-iodoascorbic acid as a tool for studying additional details of the ascorbic acid transport system. Transport studies indicate this will be a useful tool in attempts to isolated the ascorbic acid transport protein. To investigate the importance of the 2-hydroxyl group on ascorbic acid activity, we previously prepared 2-deoxy-ascorbic acid, and 2-deoxy-2-halo ascorbic acids, including 2-deoxy-2-fluoroascorbic acid, an isosteric and isopolar, non-oxidizable, analogue. The cyclic hemiketal form of 2,2-difluoro-2-deoxyascorbic acid also was prepared, a structure which corresponds to the cyclic hemiketal form of dehydroascrobic acid. Transport properties of these analogues, as well as their effects on glutarodoxin, the enzyme that reduces deoxyascorbic acid to ascorbic acid, are being investigated.