Induction of kynureninase in Neurospora.

Induction of kynureninase in a homogeneous population of mycelia in balanced growth was studied. Induced synthesis of enzyme was apparent 10 min after addition of inducers (tryptophan, kynurenine, and N-formylkynurenine). Experiments with cycloheximide-inhibited cells indicated that initiation of message transcription occurred about 4 min after addition of inducers. Lifetime of the message in the absence of inducer was of the order of 5 min. Experiments with mutants showed that N-formylkynurenine was the probable inducer of physiological importance.