抗坏血酸对大鼠脑微粒体中硫胺素二磷酸酶活性的刺激作用。

Stimulation of thiamine diphosphatase activity by ascorbic acid in rat brain microsomes.

作者信息

Iwata H, Matsuda T, Maeda S, Baba A

出版信息

Biochim Biophys Acta. 1979 Mar 7;583(2):159-66. doi: 10.1016/0304-4165(79)90423-9.

Abstract

The effect of ascorbic acid on microsomal thiamine diphosphatase activity in rat brain was examined. Ascorbic acid at 0.02--0.1 mM increased the thiamine diphosphatase activity by 20--600% and produced a significant amount of lipid peroxide, which was measured with thiobarbiturate under the same conditions as the enzyme. A lag period of about 10 min was observed in the process of stimulation of enzyme activity by ascorbic acid. The stimulation of enzyme activity and the lipid peroxidation induced by ascorbic acid were blocked by metal-binding compounds (EDTA, alpha,alpha'-dipyridyl, o-phenanthroline) and an antioxidant (N,N'-diphenyl p-phenylenediamine). GSH significantly enhanced the stimulation of enzyme activity and formation of lipid peroxide by 0.02--0.05 mM ascorbic acid. The effect of GSH was due in part to maintenance of the concentration of ascorbic acid in the medium, since GSH could convert dehydroascorbic acid, an oxidized form of ascorbic acid, to ascorbic acid.

摘要

研究了抗坏血酸对大鼠脑微粒体硫胺素二磷酸酶活性的影响。0.02 - 0.1 mM的抗坏血酸使硫胺素二磷酸酶活性提高了20% - 600%，并产生了大量脂质过氧化物，在与酶相同的条件下用硫代巴比妥酸盐进行测定。在抗坏血酸刺激酶活性的过程中观察到约10分钟的延迟期。抗坏血酸诱导的酶活性刺激和脂质过氧化被金属结合化合物（EDTA、α,α'-联吡啶、邻菲罗啉）和抗氧化剂（N,N'-二苯基对苯二胺）所阻断。谷胱甘肽（GSH）显著增强了0.02 - 0.05 mM抗坏血酸对酶活性的刺激和脂质过氧化物的形成。GSH的作用部分归因于维持培养基中抗坏血酸的浓度，因为GSH可以将抗坏血酸的氧化形式脱氢抗坏血酸转化为抗坏血酸。