Effects of Certain Hydroxamic Acids on L-Glutamate 1-Carboxy-lyase ∗

Summary

Over 50 hydroxamic acids (HA) were surveyed for inhibitory action against bacterial and vegetable glutamic acid carboxy-lyase (GCL). Appreciable activity against the bacterial enzyme was shown by 7 compounds. These 7, in addition to 2 others, also inhibited the vegetable enzyme. Four HA stimulated the activity of the vegetable enzyme, but none had a similar effect on bacterial GCL. Kinetic studies indicated that inhibition was predominantly competitive with substrate, but with the exception of 1 compound, was also antagonized by pyridoxal phosphate (PyP). Certain of the active inhibitors interacted with PyP in a nonenzymatic system as shown by changes in the ultraviolet absorption spectrum of the coenzyme, but this property was not a requisite for GCL inhibitory action.