乙硫氨酸给药和胆碱缺乏对小鼠胰腺中蛋白质羧甲基酶活性的影响。

The effects of ethionine administration and choline deficiency on protein carboxymethylase activity in mouse pancreas.

作者信息

Gilliland E L, Turner N, Steer M L

出版信息

Biochim Biophys Acta. 1981 Feb 5;672(3):280-7. doi: 10.1016/0304-4165(81)90294-4.

Abstract

Protein carboxymethylase of mouse pancreas is both soluble (70%) and particulate (30%). The Km for S-adenosylmethionine is 7.5 x 10(-7) M and the Ki for S-adenosylethionine is 1.3 . 10(-5) M. Administration of an ethionine containing diet results in a decrease in protein carboxymethylase activity. Ethionine ingestion also increases pancreatic amylase content by interfering with digestive enzyme discharge. The reciprocal changes in amylase content and protein carboxymethylase activity can be detected within 12 h of commencing the ethionine administration and are enhanced by simultaneous choline deficiency. These studies support the hypothesis that protein carboxymethylase plays an important role in secretion of exportable material. Inhibition of pancreatic protein carboxymethylase activity in vivo may be one important mechanism by which ethionine interferes with digestive enzyme discharge.

摘要

小鼠胰腺中的蛋白质羧甲基化酶既存在于可溶性部分（70%），也存在于颗粒部分（30%）。其对S-腺苷甲硫氨酸的Km值为7.5×10⁻⁷M，对S-腺苷乙硫氨酸的Ki值为1.3×10⁻⁵M。给予含乙硫氨酸的饮食会导致蛋白质羧甲基化酶活性降低。摄入乙硫氨酸还会通过干扰消化酶的释放而增加胰腺淀粉酶含量。在开始给予乙硫氨酸后的12小时内即可检测到淀粉酶含量和蛋白质羧甲基化酶活性的相反变化，同时胆碱缺乏会增强这种变化。这些研究支持了蛋白质羧甲基化酶在可输出物质分泌中起重要作用的假说。体内抑制胰腺蛋白质羧甲基化酶活性可能是乙硫氨酸干扰消化酶释放的一个重要机制。