Virusproteine, I. Isolierung von Mutanten des Phagen fd mit proteinchemischen Methoden

Abstract

The rod-shaped Escherichia coli-bacteriophage fd was prepared in a pure form. During the purification, the preparation was twice submitted to carrier-free electrophoresis. A study of the electrophoretic properties of the phage showed that its isoelectric point lies at 4.1. Mutant sheath proteins with charge differences can be separated by electrophoresis in several stages, and concentrated (up to 1:1013) against the effect of phenotypic mixing. The biological properties of phage fd make it suitable for continuous culture, so that the effect of long term exposure to mutagens in vivo can be studied. Thus the influence of weak mutagens can also be determined. Under these experimental conditions, proflavin and 2,7-diamino-fluorene are mutagenic. The continual increase in the concentration of mutants can be determined from the increase in material which is electro-phoretically different, or shows different plaque morphology. After the continuous action of proflavin or diamino-fluorene, the electro-phoretic separation was compared with the distribution curve of a control preparation. The mutant fraction ( [DELTA] + 2) was increased by 2 to 3 tenth powers. Biologically and chemically pure mutants were isolated from this fraction. The proflavin mutation is subject to photoinduction; without illumination, the rate of mutation is 100 times lower. The rate of the diaminofluorene mutation is not decreased in the dark.