日粮亮氨酸含量对反刍前羔羊组织中支链氨基酸转氨酶（EC 2.6.1.42）和支链α-酮酸脱氢酶（EC 1.2.4.4）复合体活性的影响。

Influence of dietary leucine content on the activities of branched-chain amino acid aminotransferase (EC 2.6.1.42) and branched-chain alpha-keto acid dehydrogenase (EC 1.2.4.4) complex in tissues of preruminant lambs.

Papet I, Lezebot N, Barre F, Arnal M, Harper A E

Laboratoire d'Etude du Métabolisme Azoté-INRA Theix, Ceyrat, France.

Br J Nutr. 1988 May;59(3):475-83. doi: 10.1079/bjn19880057.

Abstract

Branched-chain amino acid aminotransferase (EC 2.6.1.42; BCAAT) and branched-chain alpha-keto acid dehydrogenase (EC 1.2.4.4; BCKDH) activities were measured preruminant lamb liver, longissimus dorsi muscle, kidney, jejunum and adipose tissue, 2 h after a meal with or without an excess of leucine. 2. Skeletal muscle contained about 70% of the total basal BCAAT activities of the tissues studied whereas liver contained about 60% of the total BCKDH activities of these tissues. 3. BCAAT activities were very low in preruminant lamb tissues. BCKDH was more phosphorylated in tissues of preruminant lambs than in rats, especially in liver. These low catalytic potentialities might contribute to a low rate of branched-chain amino acid catabolism in sheep. 4. Ingestion of an excess of leucine led to an increase in liver and jejunum BCAAT activities and activation of BCKDH in jejunum.

摘要

测定了反刍前羔羊的肝脏、背最长肌、肾脏、空肠和脂肪组织中支链氨基酸转氨酶（EC 2.6.1.42；BCAAT）和支链α-酮酸脱氢酶（EC 1.2.4.4；BCKDH）的活性，测定是在进食含或不含过量亮氨酸的食物2小时后进行的。2. 骨骼肌中所含的基础BCAAT活性约占所研究组织总活性的70%，而肝脏中所含的BCKDH总活性约占这些组织总活性的60%。3. 反刍前羔羊组织中的BCAAT活性非常低。反刍前羔羊组织中的BCKDH比大鼠组织中的磷酸化程度更高，尤其是在肝脏中。这些较低的催化潜能可能导致绵羊体内支链氨基酸分解代谢速率较低。4. 摄入过量亮氨酸会导致肝脏和空肠中的BCAAT活性增加，并使空肠中的BCKDH激活。