Lowry M, Hall D E, Brosnan J T
Biochem J. 1985 Oct 15;231(2):477-80. doi: 10.1042/bj2310477.
Glycine is metabolized in isolated renal cortical tubules to stochiometric qualities of ammonia, CO2 and serine by the combined actions of the glycine-cleavage-enzyme complex and serine hydroxymethyltransferase. The rate of renal glycine metabolism by this route is increased in tubules from acidotic rats, but is not affected in vitro by decreasing the incubation pH from 7.4 to 7.1. Metabolic acidosis caused an increase in the renal activity of the glycine-cleavage-enzyme complex, but there were no changes in the activity of serine hydroxymethyltransferase or of methylenetetrahydrofolate dehydrogenase. This enzymic adaptation permits increased ammoniagenesis from glycine during acidosis. The physiological implications are discussed.
在离体肾皮质肾小管中,甘氨酸通过甘氨酸裂解酶复合体和丝氨酸羟甲基转移酶的联合作用,代谢生成化学计量的氨、二氧化碳和丝氨酸。酸中毒大鼠肾小管中通过该途径进行的肾甘氨酸代谢速率增加,但在体外将孵育pH从7.4降至7.1时,该代谢速率不受影响。代谢性酸中毒导致肾甘氨酸裂解酶复合体的活性增加,但丝氨酸羟甲基转移酶或亚甲基四氢叶酸脱氢酶的活性没有变化。这种酶适应性使得酸中毒期间从甘氨酸生成氨的过程增加。文中讨论了其生理意义。