Gainer H, Russell J T, Loh Y P
FEBS Lett. 1984 Sep 17;175(1):135-9. doi: 10.1016/0014-5793(84)80586-4.
Secretory vesicles isolated from the neural and intermediate lobes of the bovine pituitary contained a membrane-bound aminopeptidase activity which cleaved arginine from beta-LPH60-65 (Arg-Tyr-Gly-Gly-Phe-Met) and Arg-MCA. Neither methionine enkephalin (Tyr-Gly-Gly-Phe-Met) nor Substance P, which has an N-terminal arginine followed by a proline, could serve as substrates for this aminopeptidase activity; nor could cathepsin B-like or chymotrypsin-like enzyme activities be detected in the vesicle preparations. Maximal enzyme activity was at pH 6.0, and the activity was inhibited by EDTA, stimulated by Co2+ and Zn2+, but was unaffected by leupeptin, pepstatin A, phenylmethylsulfonyl fluoride and p-chloromercuribenzenesulfonate, suggesting that the enzyme is a metalloaminopeptidase. The presence of this aminopeptidase activity in secretory vesicles suggests that it may be involved in peptide prohormone processing.
从牛垂体神经叶和中间叶分离出的分泌囊泡含有一种膜结合氨肽酶活性，该活性可从β-LPH60-65（精氨酸-酪氨酸-甘氨酸-甘氨酸-苯丙氨酸-甲硫氨酸）和精氨酸-甲基香豆素酰胺（Arg-MCA）中切割精氨酸。甲硫氨酸脑啡肽（酪氨酸-甘氨酸-甘氨酸-苯丙氨酸-甲硫氨酸）和P物质（其N端为精氨酸，后面跟着一个脯氨酸）都不能作为这种氨肽酶活性的底物；在囊泡制剂中也检测不到组织蛋白酶B样或胰凝乳蛋白酶样酶活性。最大酶活性在pH 6.0时出现，该活性受到EDTA抑制，受到Co2+和Zn2+刺激，但不受亮抑酶肽、胃蛋白酶抑制剂A、苯甲基磺酰氟和对氯汞苯磺酸盐的影响，这表明该酶是一种金属氨肽酶。分泌囊泡中存在这种氨肽酶活性表明它可能参与肽原激素的加工。
