Stack G, Fricker L D, Snyder S H
Life Sci. 1984 Jan 9;34(2):113-21. doi: 10.1016/0024-3205(84)90581-2.
A sensitive radiometric assay for carboxypeptidase B-like enzymes has been developed using enkephalin convertase, an enkephalin synthesizing carboxypeptidase. The assay is based on the differential solubility of 3H-labeled substrate and product in chloroform. The substrates 3H-benzoyl-Phe-Ala-Arg or 3H-benzoyl-Phe-Leu-Arg are poorly soluble in chloroform due to the charged arginine. The products of carboxypeptidase B-like activity on these substrates, 3H-benzoyl-Phe-Ala or 3H-benzoyl Phe-Leu partition quantitatively into chloroform, allowing rapid separation of product from substrate. This assay is approximately 100 times more sensitive than a similar fluorometric assay utilizing dansyl-Phe-Ala-Arg as a substrate.
利用脑啡肽转化酶（一种合成脑啡肽的羧肽酶）开发了一种用于类羧肽酶B的灵敏放射性测定法。该测定法基于3H标记的底物和产物在氯仿中的溶解性差异。由于带电荷的精氨酸，底物3H-苯甲酰-Phe-Ala-Arg或3H-苯甲酰-Phe-Leu-Arg在氯仿中溶解度很差。这些底物上类羧肽酶B活性的产物3H-苯甲酰-Phe-Ala或3H-苯甲酰-Phe-Leu可定量分配到氯仿中，从而可快速将产物与底物分离。该测定法的灵敏度比以丹磺酰-Phe-Ala-Arg为底物的类似荧光测定法高约100倍。
