相对于细胞外亮氨酸的利用情况，细胞外2-酮异己酸在大鼠各个器官中用于蛋白质合成的情况。

Utilization for protein synthesis in individual rat organs of extracellular 2-ketoisocaproate relative to utilization of extracellular leucine.

作者信息

Shiota T, Yagi M, Walser M

机构信息

Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205.

出版信息

Metabolism. 1989 Jul;38(7):612-8. doi: 10.1016/0026-0495(89)90096-6.

DOI:10.1016/0026-0495(89)90096-6

PMID:2739573

Abstract

Rats were given constant intravenous infusions of [3H]-leucine plus [1-14C]-2-ketoisocaproate (KIC). Specific activities of plasma leucine and plasma KIC reached plateaus by two to three hours. 3H specific activity of KIC was 85% +/- 2% of that in leucine. 14C specific activity of leucine was 36% +/- 2% of that in KIC. The 14C/3H ratios in leucine and KIC were constant from the earliest sampling time (one hour) at 0.65 +/- 0.03 and 2.20 +/- 0.07, respectively. In various tissues, 14C/3H in free leucine and in tissue protein were approximately equal, but in most organs these ratios were significantly greater than the ratio 14C/3H in plasma leucine. From these data we estimate that the fraction of leucine incorporated into protein in individual organs derived from extracellular KIC rather than extracellular leucine varies from zero (in liver and bone marrow) to 35% to 45% (in brain and heart), and comprises 12% in the body as a whole.

摘要

给大鼠持续静脉输注[3H]-亮氨酸加[1-14C]-2-酮异己酸（KIC）。血浆亮氨酸和血浆KIC的比活性在两到三小时内达到平稳状态。KIC的3H比活性为亮氨酸中3H比活性的85%±2%。亮氨酸的14C比活性为KIC中14C比活性的36%±2%。从最早的采样时间（一小时）起，亮氨酸和KIC中的14C/3H比值就保持恒定，分别为0.65±0.03和2.20±0.07。在各种组织中，游离亮氨酸和组织蛋白中的14C/3H大致相等，但在大多数器官中，这些比值显著高于血浆亮氨酸中的14C/3H比值。根据这些数据我们估计，各个器官中由细胞外KIC而非细胞外亮氨酸掺入蛋白质的亮氨酸比例从零（肝脏和骨髓）到35%至45%（脑和心脏）不等，在整个身体中占12%。