Mechanism of stimulation of respiration by purines: I. Inhibitor studies

Abstract

The 2 to 3-fold stimulation of the endogenous respiration of nitrogen-starved Chlorella vulgar is Beijerinck (ATCC 11468) by purines can be suppressed by the addition of metabolic inhibitors which fall into 1 of the following 2 classes: 1. Inhibitors of sulfhydryl groups, especially dimercaptides (e. g. arsenite, cadmium ion) and 2. Compounds which act as substrates or inhibitors of known flavoprotein enzymes (e. g. hydrazine, hydroxyla-mine, semicarbazine, bisulfite, tryptamine and tyramine). Known inhibitors of electron transport via the cytochrome system stimulated the respiration of the cells and thus could not be evaluated. The purines caused a 50% decrease in the specific activity of the respired CO2 from cells which had been allowed to fix C14O2 for short periods. This effect of the purines on respiration is similarly suppressed by the inhibitors studied.