氨甲酰磷酸合成酶（氨）的Ca2+抑制作用

Inhibition of Ca2+ of carbamoylphosphate synthetase (ammonia).

作者信息

Meijer A J, van Woerkom G M, Steinman R, Williamson J R

出版信息

J Biol Chem. 1981 Apr 10;256(7):3443-6.

Abstract

The effect of Ca2+ ions on carbamoylphosphate synthetase (ammonia) (EC 6.3.4.16) of rat liver mitochondria was studied. In lysed mitochondria, carbamoylphosphate synthetase (ammonia) was inhibited by Ca2+ ions. In intact rat liver mitochondria, the rate of citrulline production from added ammonia, ornithine, and bicarbonate was inversely correlated with the magnitude of the intramitochondrial concentration of Ca2+. This effect was found at concentrations of Ca2+ which are within the physiological range. The inhibition was reversed by added Mg2+ and was not due to effects of Ca2+ on mitochondrial energy production. It is proposed that the activity of carbamoylphosphate synthetase (ammonia) may be modulated in vivo by changes in the concentration of Ca2+ ions in the mitochondrial matrix.

摘要

研究了钙离子对大鼠肝脏线粒体氨甲酰磷酸合成酶（氨）（EC 6.3.4.16）的影响。在裂解的线粒体中，氨甲酰磷酸合成酶（氨）受到钙离子的抑制。在完整的大鼠肝脏线粒体中，由添加的氨、鸟氨酸和碳酸氢盐生成瓜氨酸的速率与线粒体内钙离子浓度的大小呈负相关。在生理范围内的钙离子浓度下发现了这种效应。添加镁离子可逆转这种抑制作用，且这并非是由于钙离子对线粒体能量产生的影响。有人提出，氨甲酰磷酸合成酶（氨）的活性在体内可能受到线粒体基质中钙离子浓度变化的调节。