Watazu Y, Nagamatsu K, Shirahase Y, Kaneda N, Murao S, Okabe H
Research and Development Center, International Reagents Corporation, Kobe, Japan.
Biosci Biotechnol Biochem. 1994 Apr;58(4):745-51. doi: 10.1271/bbb.58.745.
A selective inactivating enzyme for the m-subunit of lactate dehydrogenase (LDH) was found in the culture filtrate of Penicillium citrinum KE-1, newly isolated from soil. The enzyme was purified from the culture filtrate by ammonium sulfate fractionation, column chromatography on CM-Sepharose CL-6B, and gel filtration on Sephadex G-100. The purification was 124-fold with an activity yield of 81%. The purified enzyme gave a single band, corresponding to a molecular weight of 32,000, on SDS polyacrylamide gel electrophoresis, and the isoelectric point was 9.5. The enzyme specifically inactivated the m-subunit of LDH but showed no activity on the h-subunit of LDH. The enzyme, named KE-1 proteinase, proved to be a serine-type proteinase. Limited proteolysis of native m-subunit of LDH was assumed to result in a loss of enzyme activity.
从土壤中新分离出的桔青霉KE-1的培养滤液中发现了一种能选择性使乳酸脱氢酶（LDH）的m亚基失活的酶。通过硫酸铵分级分离、CM-Sepharose CL-6B柱色谱和Sephadex G-100凝胶过滤从培养滤液中纯化该酶。纯化倍数为124倍，活性回收率为81%。纯化后的酶在SDS聚丙烯酰胺凝胶电泳上呈现单一谱带，对应分子量为32,000，等电点为9.5。该酶特异性地使LDH的m亚基失活，但对LDH的h亚基无活性。该酶被命名为KE-1蛋白酶，经证实是一种丝氨酸型蛋白酶。推测对天然LDH的m亚基进行有限的蛋白水解会导致酶活性丧失。
