Bromke B J, Hammel J M
Can J Microbiol. 1979 Jan;25(1):47-52. doi: 10.1139/m79-008.
Heavy cell suspensions of Serratia marcescens, when grown in gelatin-containing media, produce extracellular proteases which increase in specific activity in a linear fashion for 3 to 4h. During partial purification, a single peak of proteolytic activity was demonstrated by Sephadex G-100 chromatography. However, electrophoresis using 5% polyacrylamide gels discloses three proteolytically active bands. Evidence in favor of gelatin acting as an inducer of the 'proteolytic system' was provided by two observations. First, proteolytic activity is only present in media containing gelatin. Secondly, the addition of 10(-4) M rifampicin to cells growing in gelatin-containing medium plus an additional carbon source inhibits protease activity totally, but has no effect on growth. When glycerol is added to a growing cell suspension in gelatin-containing medium, growth increases, but protease specific activity decreases. This 'glycerol effect' is not due to an accumulation of active or inactive enzyme in association with the cell, nor to a decrease in the total number of proteases synthesized. Rather, glycerol, as other utilizable carbohydrates, exerts a repression which can be eliminated by 5 mM dibutyryl cyclic AMP.
粘质沙雷氏菌的重细胞悬液在含明胶的培养基中生长时，会产生细胞外蛋白酶，其比活性在3至4小时内呈线性增加。在部分纯化过程中，通过葡聚糖G - 100层析显示出一个蛋白水解活性峰。然而，使用5%聚丙烯酰胺凝胶电泳揭示了三条具有蛋白水解活性的条带。两项观察结果提供了支持明胶作为“蛋白水解系统”诱导剂的证据。第一，蛋白水解活性仅存在于含明胶的培养基中。第二，向在含明胶培养基加额外碳源中生长的细胞中添加10(-4) M利福平会完全抑制蛋白酶活性，但对生长没有影响。当向含明胶培养基中生长的细胞悬液中添加甘油时，生长增加，但蛋白酶比活性降低。这种“甘油效应”不是由于与细胞相关的活性或无活性酶的积累，也不是由于合成的蛋白酶总数减少。相反，甘油与其他可利用的碳水化合物一样，会产生一种阻遏作用，这种阻遏作用可被5 mM二丁酰环磷腺苷消除。
