The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose
The rate of lactate production from glucose in hearts is not altered by per-deuteration of glucose
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DOI：
10.1016/j.jmr.2017.09.007
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发表时间：
2017-11-01
影响因子：
2.2
通讯作者：
Malloy, Craig R.
中科院分区：
文献类型：
--
作者：
Funk, Alexander M.;Anderson, Brian L.;Malloy, Craig R.
本研究旨在确定全氘代葡萄糖是否经历动力学同位素效应（KIE），因为葡萄糖通过糖酵解并在三羧酸（TCA）循环中进一步氧化。在两组灌流的大鼠心脏中研究了氘代葡萄糖的代谢。对照组给予[U-C-13（6）]葡萄糖和[1，6-C-13（2）]葡萄糖的1：1混合物，而实验组给予[U-C-13（6），U-H-2（7）]葡萄糖和[1，6-C-13（2）]葡萄糖。通过H-1、H-2和质子去耦C-13 NMR光谱分析组织提取物。广泛的H-2-C-13标量耦合加上化学位移同位素效应中观察到的质子去耦的C-13核磁共振谱的乳酸，丙氨酸和谷氨酸。[U-C-13（6）]葡萄糖与[1，6-C-13（2）]葡萄糖转化为乳酸盐的转化率存在微小但可测量的差异（类似于8%），可能反映了醛缩酶反应中C-C键断裂的速率，但[U-C-13（6）]葡萄糖与[U-C-13（6），U-H-2（7）]葡萄糖转化为乳酸盐的转化率没有差异。这表明葡萄糖中氘的存在不会改变糖酵解通量。然而，在TCA中，氘代对葡萄糖代谢为丙氨酸和葡萄糖氧化有两种不同的影响。首先，丙氨酸在丙氨酸氨基转移酶反应中经历甲基氘与溶剂质子的广泛交换。第二，[U-C-13（6），U-H-2（7）]葡萄糖代谢为丙氨酸和谷氨酸时存在显著的动力学同位素效应。在存在[U-C-13（6），U-H-2（7）]葡萄糖的情况下，丙氨酸和乳酸盐不会与相同的丙酮酸合并液快速交换。这些研究表明，超极化[U-C-13（6），U-H-2（7）]葡萄糖的超极化C-13-乳酸盐的出现基本上不受氘动力学同位素效应的影响。(C)2017由Elsevier Inc.出版
This study was designed to determine whether perdeuterated glucose experiences a kinetic isotope effect (KIE) as glucose passes through glycolysis and is further oxidized in the tricarboxylic acid (TCA) cycle. Metabolism of deuterated glucose was investigated in two groups of perfused rat hearts. The control group was supplied with a 1:1 mixture of [U-C-13(6)]glucose and [1,6-C-13(2)]glucose, while the experimental group received [U-C-13(6),U-H-2(7)]glucose and [1,6-C-13(2)]glucose. Tissue extracts were analyzed by H-1, H-2 and proton-decoupled C-13 NMR spectroscopy. Extensive H-2-C-13 scalar coupling plus chemical shift isotope effects were observed in the proton-decoupled C-13 NMR spectra of lactate, alanine and glutamate. A small but measureable (similar to 8%) difference in the rate of conversion of [U-C-13(6)]glucose vs. [1,6-C-13(2)]glucose to lactate, likely reflecting rates of C-C bond breakage in the aldolase reaction, but conversion of [U-C-13(6)]glucose versus [U-C-13(6),U-H-2(7)]glucose to lactate did not differ. This shows that the presence of deuterium in glucose does not alter glycolytic flux. However, there were two distinct effects of deuteration on metabolism of glucose to alanine and oxidation of glucose in the TCA. First, alanine undergoes extensive exchange of methyl deuterons with solvent protons in the alanine amino transferase reaction. Second, there is a substantial kinetic isotope effect in metabolism of [U-C-13(6),U-H-2(7)]glucose to alanine and glutamate. In the presence of [U-C-13(6),U-H-2(7)]glucose, alanine and lactate are not in rapid exchange with the same pool of pyruvate. These studies indicate that the appearance of hyperpolarized C-13-lactate from hyperpolarized [U-C-13(6),U-H-2(7)]glucose is not substantially influenced by a deuterium kinetic isotope effect. (C) 2017 Published by Elsevier Inc.