Untersuchungen über Phagenlysozym. II. Isolierung und Charakterisierung von kälteempfindlichen Mutanten im Lysozymgen des Phagen T4

Abstract

With the help of bromouracil mutagenesis and selection of haloless plaques after chloroform treatment 15 haloless mutants of phage T4 were isolated. The mutant cse BU56 proved to be cold-sensitive due to a base substitution in the lysozyme gene according to the following criteria: 1 At 20 °C no plaques were formed; they appeared, however, after a temperature shift-up. 1 The energy of activation of the lysozyme reaction was significantly increased as compared to that of the wild type. This proves that an increased energy of activation of an essential enzyme-catalyzed reaction is one of the causes for cold sensitivity in microorganisms.