Inhibition of the alanine–α-oxoglutaric acid transaminase of pig-heart muscle by cyclic hydrazides

Abstract

The effect of isonicotinic acid hydrazide, picolinic acid hydrazide, benzohydrazide and isonicotinic acid hydrazide methiodide on the alanine-[alpha]-oxoglutaric acid transaminase of a pig-heart-muscle extract was studied. All were found to produce approximately 50% inhibition of glutamic acid production at a concentration of 3.3 x 10 -2 [image]. The corresponding amides were without effect on the transaminase. The mechanism of hydrazide inhibition is discussed on the basis of these findings. Of the 5 hydrazides tested only isonicotinic acid hydrazide is of therapeutic value as an anti-tuberculous drug. It is concluded that there is no correlation between the anti-tuberculous and anti-vitamin B6 activities of these hydrazides, unless the bacterial cell is selectively permeable to isoniazid alone.