Sharma V, Schwille P O
Department of Surgery, University of Erlangen, Germany.
Biochem Int. 1992 Jul;27(3):431-8.
Lactate dehydrogenase is known to act as a dismutase converting glyoxylate to oxalate and glycolate. LDH (sources: human erythrocytes, human plasma; rabbit muscle; rat liver) activity was assayed at 340 nm using glyoxylate (5.0 mmol/l) and NADH. The LDH activity (approx. % of control) in all the cases decreased respectively in the presence of 5.0 and 10.0 mmol/l of cysteine (45 and 20), cysteamine (45 and 20), and GSH (55 and 30). This decrease in LDH activity resulted in decreased oxalate production from glyoxylate (0.5 mmol/l). A 50% inhibition in oxalate production was observed in presence of 0.3 mmol/l cysteine, 0.35 mmol/l cysteamine, and 2.0 mmol/l GSH. The results suggest that the net LDH activity towards oxalate production may be regulated by the free SH-groups in the cell. This possibility needs evaluation as a tool to lower endogenous oxalate production and the associated risk of stone formation.
已知乳酸脱氢酶可作为一种歧化酶，将乙醛酸转化为草酸盐和乙醇酸盐。使用乙醛酸（5.0 mmol/L）和NADH在340 nm处测定了乳酸脱氢酶（来源：人红细胞、人血浆；兔肌肉；大鼠肝脏）的活性。在存在5.0和10.0 mmol/L半胱氨酸（45%和20%）、半胱胺（45%和20%）和谷胱甘肽（55%和30%）的情况下，所有情况下的乳酸脱氢酶活性（约为对照的百分比）均分别下降。乳酸脱氢酶活性的这种下降导致乙醛酸（0.5 mmol/L）产生的草酸盐减少。在存在0.3 mmol/L半胱氨酸、0.35 mmol/L半胱胺和2.0 mmol/L谷胱甘肽的情况下，观察到草酸盐产生受到50%的抑制。结果表明，细胞中游离的巯基可能调节了乳酸脱氢酶对草酸盐产生的净活性。作为降低内源性草酸盐产生及相关结石形成风险的一种手段，这种可能性需要评估。
