Levinthal M
J Bacteriol. 1971 Mar;105(3):1047-52. doi: 10.1128/jb.105.3.1047-1052.1971.
I identified two enzyme activities, alpha-galactosidase and a galactoside permease, required for melibiose metabolism by Salmonella typhimurium. These activities are very low under normal growth conditions, but their production can be induced by melibiose and gratuitously by melibiitol. Melibiose induction is severely inhibited by glucose, but the glucose effect can be countered by 3', 5' cyclic adenosine monophosphate. I isolated two phenotypic classes of mutants not able to utilize melibiose as a carbon source. One class, Car(-), is deficient in the phosphotransferase system. The other, Mel, lacks either alpha-galactosidase, galactoside permease, or both functions.
我鉴定出鼠伤寒沙门氏菌代谢蜜二糖所需的两种酶活性，即α-半乳糖苷酶和一种半乳糖苷通透酶。在正常生长条件下，这些活性非常低，但它们的产生可被蜜二糖诱导，也可被蜜三糖非特异性诱导。蜜二糖诱导受到葡萄糖的严重抑制，但3'，5'环磷酸腺苷可抵消葡萄糖的这种效应。我分离出两类不能利用蜜二糖作为碳源的突变体表型。一类是Car(-)，在磷酸转移酶系统方面存在缺陷。另一类是Mel，缺乏α-半乳糖苷酶、半乳糖苷通透酶或这两种功能。
