Rosin D L, Bond J S, Bradley S G
Proc Soc Exp Biol Med. 1984 Oct;177(1):112-9. doi: 10.3181/00379727-177-41919.
A cysteine metalloproteinase that degrades 125I-insulin B chain at neutral pH values was isolated from C3H mouse liver. The enzyme was partially purified from the 100,000g supernatant fraction by ammonium sulfate precipitation, DEAE-cellulose chromatography, and fast protein liquid chromatography. The molecular weight of the proteinase was estimated to be 190,000 by gel filtration on Sephadex G-200. Degradation of 125I-insulin B chain by the proteinase was inhibited by p-hydroxymercuribenzoate (PHMB) and iodoacetate (cysteine proteinase inhibitors) and by ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline (metalloproteinase inhibitors). The proteinase also degraded 125I-glucagon but did not hydrolyze 125I-insulin, leucine-2-naphthylamide, or several large proteins. Equivalent levels of EDTA- and PHMB-inhibitable 125I-insulin B chain-degrading activity were observed in the 100,000g supernatant fractions of brain, liver, lung, kidney, heart, and spleen from four mouse strains (C3H/HeN, CBA/J, ICR, and C57BL/6). High levels of 125I-insulin B chain-degrading activity were found in the particulate fraction of kidneys and lungs from these four mouse strains; these activities were inhibited by EDTA but not by PHMB. The activity of the soluble liver cysteine metalloproteinase was not altered in C3H mice treated ip with metal chelators, bacterial endotoxin, phenobarbital, dexamethasone, or insulin. Starvation for 24 or 48 hr and alloxan-induced diabetes diminished total activity of this enzyme in liver by about 50 and 30%, respectively. This soluble polypeptide-degrading enzyme appears to be ubiquitous in mice and to be regulated by nutritional conditions.
从C3H小鼠肝脏中分离出一种半胱氨酸金属蛋白酶，该酶在中性pH值下可降解125I-胰岛素B链。通过硫酸铵沉淀、DEAE-纤维素色谱和快速蛋白质液相色谱从100,000g上清液部分对该酶进行了部分纯化。通过在Sephadex G-200上进行凝胶过滤，估计该蛋白酶的分子量为190,000。对羟基汞苯甲酸（PHMB）和碘乙酸（半胱氨酸蛋白酶抑制剂）以及乙二胺四乙酸（EDTA）和1,10-菲咯啉（金属蛋白酶抑制剂）可抑制该蛋白酶对125I-胰岛素B链的降解。该蛋白酶还可降解125I-胰高血糖素，但不水解125I-胰岛素、亮氨酸-2-萘酰胺或几种大蛋白。在四种小鼠品系（C3H/HeN、CBA/J、ICR和C57BL/6）的脑、肝、肺、肾、心脏和脾脏的100,000g上清液部分中观察到了同等水平的EDTA和PHMB可抑制的125I-胰岛素B链降解活性。在这四种小鼠品系的肾脏和肺的颗粒部分中发现了高水平的125I-胰岛素B链降解活性；这些活性可被EDTA抑制，但不能被PHMB抑制。用金属螯合剂、细菌内毒素、苯巴比妥、地塞米松或胰岛素腹腔注射处理的C3H小鼠中，可溶性肝脏半胱氨酸金属蛋白酶的活性没有改变。饥饿24或48小时以及四氧嘧啶诱导的糖尿病分别使肝脏中该酶的总活性降低约50%和30%。这种可溶性多肽降解酶似乎在小鼠中普遍存在，并受营养状况的调节。
