Purification and characterization of an extracellular muramidase of Clostridium acetobutylicum ATCC 824 that acts on non-N-acetylated peptidoglycan
Purification and characterization of an extracellular muramidase of Clostridium acetobutylicum ATCC 824 that acts on non-N-acetylated peptidoglycan
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DOI：
10.1128/aem.58.4.1075-1081.1992
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发表时间：
1992-04
影响因子：
4.4
通讯作者：
C. Croux;B. Canard;Gérard Goma;P. Soucaille
中科院分区：
文献类型：
--
作者：
C. Croux;B. Canard;Gérard Goma;P. Soucaille
从丙酮丁醇梭菌ATCC 824中分离出一种对非N-乙酰化肽聚糖具有裂解活性的胞外酶。通过阴离子交换层析和凝胶过滤将裂解酶纯化至均一，回收率为24%。该酶为单体，估计分子量为41，000，等电点为3.8。它已被表征为一种胞壁酶，其23个氨基酸的N末端显示39%的同源性与真菌Chalaropsis属的N，O-二乙酰胞壁酶。该胞壁酶水解纯化的细胞壁在最佳pH值为3，最大速度为9.1 μ mol的还原糖释放min-1毫克的胞壁酶-1和浓度的细胞壁给出了0.01毫克ml-1的半最大速率。氨基葡萄糖、N-乙酰氨基葡萄糖、Hg ~（2+）、Fe ~（3+）和Ag ~+对该酶活性有抑制作用，但胆碱对该酶活性无抑制作用。溶菌酶-肽聚糖复合物在链完全水解之前迅速解离，并在另一个肽聚糖链上随机重新缔合。溶菌酶的亲和力受蛋白质含量和细胞壁乙酰化程度的影响。
An extracellular enzyme showing lytic activity on non-N-acetylated peptidoglycan has been isolated from Clostridium acetobutylicum ATCC 824. The lytic enzyme was purified to homogeneity by anion-exchange chromatography and gel filtration, with a recovery of 24%. The enzyme was monomeric and had an estimated molecular weight of 41,000 and an isoelectric point of 3.8. It has been characterized as a muramidase whose 23-amino-acid N terminus displayed 39% homology with the N,O-diacetyl muramidase of the fungus Chalaropsis sp. The muramidase hydrolyzed purified cell walls at an optimum pH of 3, with a maximum velocity of 9.1 mumol of reducing sugars released min-1 mg of muramidase-1 and a concentration of cell walls giving a half-maximum rate of 0.01 mg ml-1. Its activity was inhibited by glucosamine, N-acetylglucosamine, Hg2+, Fe3+, and Ag+ but not by choline. The muramidase-peptidoglycan complex rapidly dissociated before total hydrolysis of the chain and randomly reassociated on another peptidoglycan chain. The affinity of the muramidase was affected by the protein content and the acetylation of the cell wall.