Isolation of unselected mutants of alkaline phosphatase in Escherichia coli through nitrosoguanidine comutation and comparison with natural variants

摘要: We have devised a general procedure to isolate enzymatic variants without selecting or screening for related phenotypic peculiarities of the organism. A high mutation rate at phoA, structural gene alkaline phosphatase, is found among N-methyl-N'-nitro-N-nitrosoguanidine-induced proC revertants Escherichia coli. About 1.6% such lack and many others exhibit altered enzyme parameters. Three mutants studied in detail had full activity but differed from wild type electrophoretic mobility, thermostability, and, one case, optimum pH activity. Four other phosphatase were discovered survey 50 natural E. coli isolates; their mobility thermostability different those type. Natural induced are similar enough suggest absence strong selective pressures populations.