External and internal forms of yeast aminopeptidase II.
External and internal forms of yeast aminopeptidase II.
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酵母氨肽酶 II 的外部和内部形式。
DOI：
10.1111/j.1432-1033.1979.tb13099.x
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
K. Röhm
中科院分区：
文献类型：
--
作者：
J. Frey;K. Röhm
1.酿酒酵母的完整细胞催化各种氨肽酶底物的水解。这种活性不是由于底物和产物的渗透，而是由外部酶产生的。2.根据其底物特异性以及pH和抑制剂的影响，该酶被鉴定为氨肽酶II。3.约40%的总氨肽酶II活性是未处理的指数生长的细胞检测。在细胞壁的酶消化过程中，高达三分之二的外部酶被释放到培养基中，而渗透压休克则几乎没有释放酶。膜制剂只含有少量的氨肽酶II，因此，外部酶的本地化似乎是类似的所谓的“周质”酵母水解酶。4.通过细胞化学方法，氨肽酶II在细胞包膜中的存在是可视化的。5.与氨肽酶II相反，酵母二肽酶是完全细胞内的酶。
1. Intact cells of Saccharomyces cerevisiae catalyze the hydrolysis of various aminopeptidase substrates. This activity is not due to permeation of substrates and products but exerted by an external enzyme. 2. From its substrate specificity and the effects of pH and inhibitors the enzyme was identified as aminopeptidase II. 3. About 40% of total aminopeptidase II activity is detectable with untreated exponentially growing cells. Up to two thirds of the external enzyme is released into the medium during enzymic digestion of the cell wall, while little enzyme is liberated by osmotic shock. Membrane preparations contained only small amounts of aminopeptidase II; thus, the localization of the external enzyme appears to be similar to that of the so-called 'periplasmic' yeast hydrolases. 4. By cytochemical methods the presence of aminopeptidase II in the cell envelope was visualized. 5. In contrast to aminopeptidase II, yeast dipeptidase is an entirely intracellular enzyme.