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Abstract
SUMMARY: A simple method for purification of tryptophan desmolase from Neurospora crassa in a good yield is described. No difference could be detected between the tryptophan desmolase extracted from a back-mutated strain of mutant C 83 and that from the wild-type strain. Michaelis constants with respect to the substrates indole and serine and the co-factor pyridoxal phosphate were measured as the basis for possible differences. It is shown that the concentration of tryptophan desmolase in the organism can be determined by genes other than those which induce a tryptophan requirement. Crosses of a histidine-requiring mutant to wild type yielded mutant progeny with 2 to 3 times the normal activity and progeny with no detectable activity under certain conditions. The lack of activity appears to be due to the production of an inhibitor.
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