A new protamine-specific-metalloproteinase from Penicillium

从桔青霉（Penicilliumcitrinum）中分离出一种金属蛋白酶，它对核碱性蛋白和氧化胰岛素B链具有独特的专一性，每摩尔酶含1克原子锌，分子量为17，000。测定了该酶95%的氨基酸序列。研究了全酶和脱辅基酶的圆二色性。一个克原子的锌不仅是酶的活性而且是酶的构象的必需组分，该酶在pH7.0时对碱性核蛋白如鲱精、三文鱼红和组蛋白具有特异性活性。蛋白酶在氧化胰岛素B链上切割的起始位点在Tyr 16-Leu 17之间，并注意到另外的位点Glu 13-Ala 14和Ala 14-Leu 15。水解由5 - 13个氨基酸组成的小肽，如缓激肽、强啡肽-A、α-新内啡肽、神经降压素、促黄体激素释放激素、α-黑素细胞。E刺激素、P物质和鸡脑五肽。

It was found that a metalloproteinase from Penicillium citrinum has a specificity unique from those of other metalloproteinases on nuclear basic proteins and oxidized insulin B-chain.The enzyme was found to contain 1 gram-atom zinc per mole of enzyme with the molecular weight of 17, 000. About 95% of the amino acid sequence of the enzyme was determined. The circular dichroism(CD)of the holo- and apo-enzymes has been investigated. One gram-atom of zinc was essential component of the enzyme not only the activity but also the conformation.The enzyme was specifically active on basic nuclear protein& such as clupeine, salmine and histone at pH 7.0. The initial site of cleavage on the oxidized insulin B-chain by the proteinase was between Tyrl6-Leul7, and additional sites, Glul3-Alal4 and Alal4-Leul5 were noted. Hydrolyses of small peptides consisting 5 - 13 amino acids such as bradykinin, dynorphin-A, alpha-neoendorphin, neurotensin, luteinizing hormone releasing hormone, alpha-melanocyt. e stimulating hormone, substance P and chicken brain pentapeptide were noted.