Levine M, Lentz K E, Kahn J R, Dorer F E, Skeggs L T
Circ Res. 1976 Jun;38(6 Suppl 2):90-4. doi: 10.1161/01.res.38.6.90.
Previous investigators have reported finding a high molecular weight (HMW) renin in various species which is activated by acidification. Two laboratories have reported that a decrease in molecular weight of the renin accompanies the acidification step. This report describes the partial purification of an HMW renin from hog kidney extracts which had previously been acidified to pH 2.5. The HMW renin, with a molecular weight of 57,000-59,000, constitutes only a small, relatively constant fraction of the total renin isolated. Omission of the acidification step or initial acidification to pH 1.6 does not change the amount of HMW renin significantly. The HMW renin attacks the protein substrate to produce angiotensin at about one-fourth the rate expected, based upon the rate at which it cleaves the tetradecapeptide substrate or a model nonapeptide substrate. It is inactivated by antiserum to hog kidney renin prepared in dogs. It is less stable than hog renin when stored at 0 degrees C. The HMW renin has a pH optimum between 6.5 and 7.0. It is not activated by acidification to pH 3, nor by tryptic or peptic digestion. We have been unable to activate HMW renin or to change its molecular weight by procedures reported by other investigators and therefore conclude that the HMW renin differs from material previously reported and may be an isoenzyme of renin.
先前的研究人员报告称，在各种物种中发现了一种高分子量（HMW）肾素，它可被酸化激活。两个实验室报告说，肾素分子量的降低伴随着酸化步骤。本报告描述了从先前已酸化至pH 2.5的猪肾提取物中部分纯化HMW肾素的过程。分子量为57,000 - 59,000的HMW肾素仅占分离出的总肾素的一小部分，且比例相对恒定。省略酸化步骤或将初始酸化至pH 1.6不会显著改变HMW肾素的量。基于其切割十四肽底物或模型九肽底物的速率，HMW肾素攻击蛋白质底物产生血管紧张素的速率约为预期速率的四分之一。它可被用狗制备的抗猪肾肾素抗血清灭活。在0℃储存时，它比猪肾素更不稳定。HMW肾素的最适pH在6.5至7.0之间。它不会被酸化至pH 3激活，也不会被胰蛋白酶或胃蛋白酶消化激活。我们无法通过其他研究人员报告的方法激活HMW肾素或改变其分子量，因此得出结论，HMW肾素与先前报道的物质不同，可能是肾素的一种同工酶。
