Methionine Sulphoximine and some Enzyme Systems involving Glutamine

Abstract

METHIONINE sulphoximine is toxic to a wide range of living organisms. Apart from the neurotoxic effect upon animals and the inhibition of the growth of certain bacteria, it also inhibits the germination of seedlings and the larval development of the insect Tribolium confusum (unpublished observations). In an earlier report¹ it was shown that the toxic effect upon Leuconostoc mesenteroides is reversed by l-glutamine, and it is useful to know whether in higher organisms methionine sulphoximine also interferes with enzyme processes involving glutamine. It appeared pertinent, as a first approach, to examine the effect of methionine sulphoximine on the enzyme systems concerned in the synthesis of glutamine^2,3 and the transfer of glutamyl groups^4–8, as these are widely distributed and are considered important in the primary stages of peptide bond formation^9,10. In addition to this general aspect there is a more particular interest attached to the question of whether, in mammalian tissues, there may be a relationship between sulphoximine and glutamine. This arises from the work of Tower and K. A. C. Elliott¹¹, who have shown that on incubation of slices of cerebral cortex tissue, from animals convulsed with methionine sulphoximine, bound acetylcholine fails to increase, but that this anomalous effect is reversed if glutamine or methionine is added to the suspending medium.