A phage endolysin was isolated from phage HM 2-induced lysate of Clostridium saccharoperbutylacetonicum (ATCC 13564), by precipitation with ammonium sulfate, and DEAE-cellulose column chromatography. This endolysin lysed the cell walls and peptidoglycans of C. saccharoperbutylacetonicum and some other clostrideia, but hardly their living whole cells, formalin-treated whole cells and heat-treated whole cells. It had two different lytic activities, which were not separated even by use of electrophoresis on isoelectric focusing. One (activity I) was a N-acetylmuramidase, which cleaved β-1, 4 bonds between N-acetylmuramic acid and N-acetylglucosamine of peptidoglycan, and its optimum pH was 4.0. The other (activity II) digested the cell wall at optimal pH 5.0, but not peptidoglycan. This digestion of cell wall by the latter was accompanied by the release of NH2-terminal D-alanine, without concomitant release of NH2-terminal L-alanine and of COOH-terminal amino acids. Therefore, it was considered that the activity II might attack on the bonds of D-alanine in teichoic acid-like substance of cell wall.
HM2ファ-ジが感染したClostridium saccharopetbutylacetonicum (ATCC 13564)の溶菌液から,この宿主菌の細胞壁の他に,C. kaneboi, C. sporogenesの細胞壁を溶解する溶菌酵素を,硫安塩析,DEAD-セルロースカラムクロマトグラフィーによって分離精製した.本辞素は,Clostridium属細菌の生菌体やホルマリン処理菌体を溶解せず,細胞壁とペプチドグリカンのみを溶解するという高い基質特異性を有していた.本酵素には,至適pH4.0で,ペプチドグリカンから還元基のみを遊離させてこれを分解する酵素作用Ⅰと,至適pH5.0で, 細胞壁からのみアミノ基を遊離させる辞素作用Ⅱが存在した. 酵素作用Ⅰはペプチドグリカンのグリカン部を切断するN-acetylmuramidaseの作用であった. 酵素作用Ⅱは,分解生成物のN-末端アミノ基がD-アラニンであること,ペプチドグリカンに対して全く作用しないことなどから,細胞壁に存在するタイコ酸様物質のD-アラニンを遊離させる作用であると考えられた.