Alanine BCAA catabolism

BCAA catabolism, 209 chemical structure, 18 plasma concentrahon, 465 waste nitrogen and, 209-210 Alanine aminotransferase, 426 Alanine cycle, amino transferases and, 427-428... 

Net breakdown of muscle can occur with either exercise or prolonged fasting. The mechanisms that control the breakdown of the various types of protein found in muscle are not well understood. It has, however, been established that while the branched-chain amino acids (BCAAs) released tend to be oxidized for energy in the muscle cell, other released amino acids enter the bloodstream for catabolism, and perhaps gluconeogenesis, in the liver Examination of the amino acids released from skeletal muscle reveals an apparent anomaly alanine accounts for or ly about 6% of the amino acids of muscle, but for about 35% of the amino acids released from muscle during exerdse. 

The BCAA (valine, leucine, and isoleucine) form a significant portion of the composition of the average protein and can be converted to tricarboxylic acid (TCA) cycle intermediates and used as fuels by almost all tissues. They are also the major precursors of glutamine. Except for the BCAA and alanine, aspartate, and glutamate, the catabolism of amino acids occurs principally in the liver. 

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