Carbohydrate Metabolism in Protozoa and Metal-binding Substances

Abstract

THE effect of cyanide on fermentation processes of living cells, which is on the whole much smaller than that on respiration, has been interpreted in the past as due to the interception by cyanide of intermediary products of fermentation, rather than to complex formation with heavy-metal catalysts; as pointed out again only recently, “no enzyme of fermentation is known to require the addition of a heavy metal except the aldolase of yeast”¹. That not all living cells conform with this view has already been indicated by our previous work on the metabolism of certain Protozoa, and in particular by the finding that the anaerobic fermentation of glucose by the flagellate Trypanosoma lewisi is inhibited 50 per cent by 0.007 M cyanide and also by such metal-binding substances as 2 : 2′-dipyridyl and 8-hydroxy-quinoline²; on the other hand, the same metal-binding substances have been shown to have a small but definite stimulating effect on intracellular glycogen fermentation in the ciliate Tetrahymena pyriformis³. These effects have now been investigated further.