FOLYL POLYGLUTAMATES AND FOLATE-DEPENDENT ENZYMES

目前，我们掌握的信息仅限于以下几个方面 其中叶基多谷氨酸盐的链长用来引导 一个碳单位通过哺乳动物细胞中的竞争途径。这个 本文描述的研究旨在提供有关 不同叶酸依赖酶对细胞数量的特异性 叶酸共底物的聚谷氨酸“尾巴”中的谷氨酰残基 抑制剂。这样的研究可以用来预测代谢流量的模式。 用于不同聚谷氨酸链长的叶酸衍生物。他们是 也有助于预测临床上多发性谷氨酸氨化的影响 重要的抗叶酸药物如甲氨蝶呤对各种 叶酸依赖反应。此外，我们认为， 叶基多谷氨酸底物可能在机理研究中非常有用， 特别是在它们导致添加顺序发生变化的情况下 底物与用单谷氨酸观察到的添加顺序的比较 叶酸底物。在目前的提案中，我们计划继续我们的 叶基多谷氨酸与蛋白质相互作用的研究 使用稳态动力学组合的叶酸依赖酶 研究和结构研究。我们将继续研究 亚甲基四氢叶酸脱氢酶、胸苷合成酶、丝氨酸 羟甲基转移酶和亚甲基四氢叶酸还原酶，并将 启动对AICAR和GAR转移酶和蛋氨酸合成酶的研究。

At present we have only limited information available on the extent to which the chain length of folylpolyglutamates serves to direct the flux of one carbon units through competing pathways in mammalian cells. The studies described herein are aimed at providing basic information on the specificities of various folate-dependent enzymes for the number of glutamyl residues in the polyglutamate "tail" of folate cosubstrates and inhibitors. Such studies can be used to predict patterns of metabolic flux for folate derivatives of differing polyglutamate chain length. They are also useful for predicting the effect of polyglutamylation of clinically important antifolate drugs such as methotrexate on the various folate-dependent reactions. In addition, we believe that folylpolyglutamate substrates may prove very useful in mechanistic studies, particularly where they lead to changes in the order of addition of substrates as compared to the order of addition observed with monoglutamate folate substrate. In the present proposal we plan to continue our examination of the interactions of folylpolyglutamates with folate-dependent enzymes using a combination of steady-state kinetic studies and structural studies. We will continue studies on methylenetetrahydrofolate dehydrogenase, thymidylate synthase, serine hydroxymethyl-transferase and methylenetetrahydrofolate reductase, and will initiate studies on AICAR and GAR transformylase and methionine synthase.