Nakagawa H, Endo Y, Ohtaki S
Acta Endocrinol (Copenh). 1981 Nov;98(3):390-5.
A leupeptin-sensitive new protease was partially purified from hog thyroid lysosomes. The purification procedure included solubilization by hypotonic treatment of lysosomes, and Sephacryl S-300 and Sephadex G-100 gel chromatography, and the purification ratio was 10-fold from lysosomes. The pH optimum of the protease activity was around 5.5 and its molecular weight was estimated to be 22 000 by gel filtration. 2-Mercaptoethanol activated the hydrolysis of protein substrates and its effect was most pronounced in the case of thyroglobulin as substrate. Among the inhibitors used, leupeptin, antipain, toluenesulfonyl-lysine chloromethyl ketone and, to a lesser degree, chymostatin and toluene-sulfonyl-phenylalanine chloromethyl ketone effectively inhibited the hydrolysis of casein by the enzyme at pH 5.5, whereas pepstatin did not inhibit the activity significantly. The enzyme activity was also inhibited by sulfhydryl inhibitors such as iodoacetamide, p-chloromercuribenzoate, and N-ethylmaleimide. The release of iodoamino acids from thyroglobulin by the enzyme was inhibited in the same manner by the inhibitors used in the hydrolysis of casein. The physiological role of the new protease is discussed in comparison with cathepsin B and L found in liver lysosomes.
从猪甲状腺溶酶体中部分纯化出一种对亮抑蛋白酶肽敏感的新型蛋白酶。纯化过程包括通过低渗处理溶酶体使其溶解，以及使用Sephacryl S - 300和Sephadex G - 100凝胶色谱法，纯化倍数相对于溶酶体为10倍。该蛋白酶活性的最适pH约为5.5，通过凝胶过滤法估计其分子量为22000。2 - 巯基乙醇可激活蛋白质底物的水解，在以甲状腺球蛋白为底物的情况下其作用最为明显。在所使用的抑制剂中，亮抑蛋白酶肽、抗蛋白酶、甲苯磺酰赖氨酸氯甲基酮，以及在较小程度上的抑糜酶素和甲苯磺酰苯丙氨酸氯甲基酮，在pH 5.5时能有效抑制该酶对酪蛋白的水解，而胃蛋白酶抑制剂对其活性的抑制作用不显著。该酶的活性也受到碘乙酰胺、对氯汞苯甲酸和N - 乙基马来酰亚胺等巯基抑制剂的抑制。在酪蛋白水解中使用的抑制剂以相同方式抑制该酶从甲状腺球蛋白中释放碘氨基酸。本文将这种新型蛋白酶的生理作用与肝脏溶酶体中发现的组织蛋白酶B和L进行了比较讨论。
