Potter D M, McDonald W J, Dunn P M, Metcalfe J
Circ Res. 1978 Dec;43(6):832-9. doi: 10.1161/01.res.43.6.832.
We found an acid extract of normal dog kidneys to contain two distinct molecular weight forms of renin-like activity. Gel filtration chromatography showed peaks of activity as estimated molecular weights of 65,000 and 41,000. The high molecular weight fraction (HMW) comprised only 1% of the total activity of the extract. Both HMW and low molecular weight (LMW) fractions were inhibited by anti-human renin antibody and had similar broad pH-dependent activity optima between pH 6.0 and 7.5 in homologous substrate. The Michaelis constant (Km) of HMW was 3.6 times the Km of LMW. Both renins bound reversibly to concanavalin A-Sepharose with comparable affinities. HMW and LMW eluted from DEAE-Sephadex at similar salt concentrations without conversion of HMW to LMW. Transient acidification effected partial conversion of HMW to LMW without changing the total activity. Preincubation of HMW with trypsin increased the activity 40% and effected complete conversion of HMW to LMW. The apparent molecular weight difference between HMW and LMW is probably due to a covalently bound fragment(s) and not to a noncovalently bound moiety such as has been described in the rabbit and the hog. Both HMW and LMW are glycoproteins whose terminal sugar constituents possibly are similar. HMW dog renin is a new molecular form of renin that is convertible to a more active lower molecular weight renin with tryptic proteolysis.
我们发现正常犬肾的酸提取物含有两种不同分子量形式的肾素样活性。凝胶过滤色谱显示活性峰，估计分子量分别为65,000和41,000。高分子量部分（HMW）仅占提取物总活性的1%。HMW和低分子量（LMW）部分均被抗人肾素抗体抑制，并且在同源底物中，在pH 6.0至7.5之间具有相似的宽泛pH依赖性活性最佳值。HMW的米氏常数（Km）是LMW的3.6倍。两种肾素都以相当的亲和力与伴刀豆球蛋白A - 琼脂糖可逆结合。HMW和LMW从DEAE - 葡聚糖凝胶以相似的盐浓度洗脱，且HMW未转化为LMW。短暂酸化导致HMW部分转化为LMW，但总活性不变。HMW与胰蛋白酶预孵育可使活性增加40%，并使HMW完全转化为LMW。HMW和LMW之间明显的分子量差异可能是由于共价结合的片段，而不是像在兔和猪中所描述的非共价结合部分。HMW和LMW都是糖蛋白，其末端糖成分可能相似。犬HMW肾素是一种新的肾素分子形式，可通过胰蛋白酶解作用转化为活性更高的低分子量肾素。
