Activation of tryptophan pyrrolase by benzylhydrazine

The mechanism responsible for the activation of tryptophan pyrrolase (TP) by benzylhydrazine (BZH) was investigated. The increase in holo/apo ratio of rat TP activity after addition of BZH in concentration of 1 x 10(-4)M, which is a major metabolite of isocarboxazid (ISOC), was higher than those in mice and guinea pigs. In addition, treatment with ISOC to rats (50 mg/kg i.p.) resulted in a significant increase in TP activity. These results suggested that the BZH-induced elevation of TP is at least in part due to a stimulation of conjugation step of TP activity.