MUSCLE GLYCOLYTIC ENZYME DEFICIENCY METABOLIC & PHYSIOLOGIC EFFECTS

越来越多的证据表明，Krebs TCA周期的一个组织 相关的酶存在于线粒体基质中。确实是 最近报道[2-13C]或[3-13C]丙酸的代谢 在酵母中产生了不对称标记的丙氨酸。这 观察结果至少有两种解释。有可能会有一个 不存在对称中间体的氧化途径 丙酸直接转化为丙酮酸。这样的一条途径一直是 在一些生物中描述，但不在酿酒酵母中描述。 或者，如果Krebs TCA循环酶高度组织化， 可以想象中间体的取向守恒转移 在琥珀酸硫激酶、琥珀酸脱氢酶和富马酸酶之间 解释一下这个有些出乎意料的结果。以测试是否存在 中间体琥珀酸和富马酸从一种活性物质转移 在没有将其释放到批量阶段的情况下，我们检查了 [4-13C]谷氨酸在酿酒酵母中的代谢13C 形成的天冬氨酸的[2-13C]/[3-13C](C2/C3)比大于 1.当[2-13C]乙酸酯与酵母孵育时，C2/C3天冬氨酸 2分钟时比率为1.5，约10分钟后降至1.0 孵化。这些结果表明，取向是守恒的 转移发生在琥珀酸硫激酶和琥珀酸处。 克雷布斯循环的脱氢酶步骤。我们正在研究 柠檬酸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： (09/01/97-08/31/98)

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)