Desantiago S, Alemán G, Hernández-Montes H
Unidad de Investigación Médica en Nutrición, Hospital de Pediatria, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México, D.F.
Arch Med Res. 1996 Winter;27(4):443-8.
Transamination reaction is the first step in the catabolism of most of the L-amino acids. Alanine is an important molecule in the inter-organ nitrogen transport, conveying them from muscle to the liver. Amino groups from this amino acid are generally first transferred to alpha-ketoglutarate in the cytosol of liver cells to form glutamate and leaving behind the corresponding alpha-keto acid analog. Measurements of the alanine aminotransferase (EC2.6.1.2.) activity were compared in liver, mammary gland and skeletal muscle in virgin, lactating and weaning dam rats. In this study liver was the principal tissue involved in alanine transamination, while muscle showed a reduction in the enzyme activity during lactation. Results indicate an increase in alanine amino-transferase activity in the mammary gland during lactation and weaning when compared with virgin rats. This suggests that mammary gland during lactation is an important extra-hepatic tissue involved in the metabolism of alanine and probably shunted into the pathways for amino group metabolism in terms of nitrogen economy.
转氨反应是大多数L-氨基酸分解代谢的第一步。丙氨酸是器官间氮转运中的重要分子，将氮从肌肉输送到肝脏。该氨基酸的氨基通常首先在肝细胞胞质溶胶中转移到α-酮戊二酸，形成谷氨酸，并留下相应的α-酮酸类似物。比较了未生育、哺乳期和断奶期母鼠肝脏、乳腺和骨骼肌中丙氨酸转氨酶（EC2.6.1.2.）的活性。在本研究中，肝脏是参与丙氨酸转氨作用的主要组织，而肌肉在哺乳期酶活性降低。结果表明，与未生育大鼠相比，哺乳期和断奶期乳腺中丙氨酸转氨酶活性增加。这表明哺乳期乳腺是参与丙氨酸代谢的重要肝外组织，从氮代谢角度来看，可能分流到氨基代谢途径中。
