Tankersley D L, Fournel M A, Schroeder D D
Biochemistry. 1980 Jul 8;19(14):3121-7. doi: 10.1021/bi00555a001.
A 28 000 molecular weight activator of prekallikrein was isolated from human plasma, and the kinetics of its enzymic activity toward prekallikrein was investigated. The activation follows Michaelis-Menten kinetics with a kcat of approximately 3 S(-1); Km is strongly dependent upon the ionic strength. Under suitable conditions the activation obeys first-order kinetics, and the first-order rate constant may be used to quantitate prekallikrein activator activity. Thus a two-stage assay, in which the first step involves the activation of prekallikrein by the activator and the second step quantitates the kallikrein generated, was developed to allow the measurement of prekallikrein activator in biologic samples. The prekallikrein activator content of therapeutic protein solutions, as determined by means of this assay, correlated well with the hypotensive activity of these solutions as determined in an animal model.
从人血浆中分离出一种分子量为28000的前激肽释放酶激活剂，并研究了其对前激肽释放酶的酶活性动力学。激活过程遵循米氏动力学，催化常数kcat约为3 s⁻¹；米氏常数Km强烈依赖于离子强度。在合适的条件下，激活遵循一级动力学，一级速率常数可用于定量前激肽释放酶激活剂活性。因此，开发了一种两步分析法，第一步是激活剂激活前激肽释放酶，第二步是对产生的激肽释放酶进行定量，以测定生物样品中的前激肽释放酶激活剂。通过该分析法测定的治疗性蛋白质溶液中的前激肽释放酶激活剂含量，与在动物模型中测定的这些溶液的降压活性密切相关。
