Studies on the effect of certain enzymic poisons on the metabolism of storage organs. VII. The effect of iodoacetate on the metabolism of nitrogen compounds by radish root slices

Feeding with various nitrogen compounds led to marked changes in the total amount and in the relative composition of the nitrogen pool in the radish slices. Possible modes of utilization of these compounds are given. lodoacetate greatly retarded the uptake and utilization of NH4C1 and aspartic acid. Whereas the uptake of KNG3 was inhibited by iodoacetate, its utilization was markedly enhanced. The losses of nitrogen fractions from the differently treated tissues were almost recovered in the culture media. The marked losses in carbohydrates would almost correspond in amount with the increased C02 output and with the synthesis of nitrogenous constituents. However, some of the lost carbohydrates from tissues treated with iodoacetate + either NH4C1 or aspartic acid could be markedly accounted for in the culture media. The rise in C02 output in iodoacetate is mainly attributed to increased accessibility, in the metabolic region, of substrates to enzymes. The differential rates of C02 production by tissues incubated in nitrogen media, either alone or supplemented with iodoacetate are interpreted on the bases that different rates of uptake of nitrogen compounds and of utilization of ATP are possible. Also the relation between nitrogen assimilation and the breakdown of carbohydrates is discussed.