MUSCLE GLYCOLYTIC ENZYME DEFICIENCY METABOLIC & PHYSIOLOGIC EFFECTS

有越来越多的证据表明，一个组织的克雷布斯TCA循环 和相关酶存在于线粒体基质内。 这是 最近报道，[2- 13 C]或[3- 13 C]丙酸盐的代谢 在酵母中产生不对称标记的丙氨酸。 这 观察至少有两种解释。 也有可能 氧化途径，没有对称的中间体存在的 将丙酸盐直接转化为丙酮酸盐。 这样一条道路， 在一些生物中描述，但在酿酒酵母中没有。 或者，如果克雷布斯TCA循环酶是高度组织化的， 我们可以看到中间体的方向保守转移 琥珀酸硫激酶、琥珀酸脱氢酶和琥珀酸脱氢酶之间， 解释这个有点出乎意料的结果。 以测试是否 中间体琥珀酸盐和富马酸盐从一种活性物质转移 网站到另一个没有他们释放到一个散装阶段，我们研究了 [4- 13 C]谷氨酸在酿酒酵母中的代谢。 的13 c 形成的天冬氨酸显示[2- 13 C]/ [3- 13 C]（C2/C3）比大于 1. 当[2- 13 C]乙酸与酵母一起孵育时，C2/C3天冬氨酸 比率在2分钟时为1.5，并且在约10分钟后降低至1.0。 孵化 这些结果表明， 转移发生在琥珀酸硫激酶和琥珀酸 三羧酸循环的脱氢酶步骤。 我们正在研究 柠檬酸盐融合蛋白转化酵母细胞的代谢 合酶和乌头酸酶。 （服务13）报告期： (09（1997年1月至1998年8月31日）

There is mounting evidence that an organization of Krebs TCA cycle and associated enzymes exists within the mitochondrial matrix. It was recently reported that the metabolism of [2-13C] or [3-13C] propionate in yeast gave rise to asymmetrically labeled alanine. This observation has at least two explanations. It is possible that an oxidative pathway with no symmetrical intermediates exists for the direct conversion of propionate to pyruvate. Such a pathway has been described in some organisms but not Saccharomyces cerevisiae. Alternatively, if the Krebs TCA cycle enzymes are highly organized, one could visualize an orientation conserved transfer of intermediates between succinate thiokinase, succinate dehydrogenase, and fumarase to explain this somewhat unexpected result. To test whether the intermediates succinate and fumarate are transferred from one active site to another without their release to a bulk phase, we examined the metabolism of [4-13C] glutamate in Saccharomyces cerevisiae. The 13C aspartate formed showed a [2-13C]/ [3-13C] (C2/C3) ratio greater than 1. When [2-13C] acetate is incubated with yeast, the C2/C3 aspartate ratio is 1.5 at 2 min and decreases to 1.0 after about 10 min of incubation. These results indicate that orientation conserved transfer occurs at the succinate thiokinase and succinate dehydrogenase steps of the Krebs cycle. We are examining the metabolism of yeast cells transformed with a fusion protein of citrate synthase and aconitase. (Service 13) REPORT PERIOD: (09/01/97-08/31/98)