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棉花病原体Xanthomonas campestris pv.malvacearum在酪蛋白(脱脂奶)存在下生长时产生胞外蛋白酶活性,其中至少包含3种蛋白酶,表观分子量分别为29(蛋白酶-1)、38和43kD。 蛋白酶-1被纯化,其最适pH在5.5～7.5之间。抑制研究表明蛋白酶-1可被Phosphoramidone、EDTA及1,10-邻二氮杂菲抑制,然后用锌离子温育重新激活,说明这是一个金属蛋白酶。发现蛋白酶-1特异地裂解肽链的天冬氨酸残基或半胱氯酸残基的氨基端侧,这种高度的肽键专一性预示这个酶在蛋白质链顺序分析中及由较大蛋白质制备特定多肽方面可能十分有用。
The cotton pathogen Xanthomonas campestris pv. Malvacearum produces extracellular protease activity when grown in the presence of casein (skim milk), which contains at least three proteases with apparent molecular weights of 29 (protease-1), 38 and 43 kD, respectively. Protease-1 is purified and its optimum pH is between 5.5 and 7.5. Inhibition studies show that protease-1 can be inhibited by Phosphoramidone, EDTA and 1,10-phenanthroline, and then reactivated by zinc ion incubation, indicating that this is a metalloprotease. It was found that protease-1 specifically cleaves the amino-terminal side of the aspartic acid residue or the cysteic acid residue of the peptide chain. This high degree of peptide-bond specificity predicts that this enzyme is highly conserved in protein sequence analysis and by larger A protein may be very useful in preparing a particular polypeptide.