1 Department of Chemistry, Faculty of Science, Københavns Universitet2 Section of Renal and Vascular Research, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet3 Department of Chemistry, University of Copenhagen4 Section of Renal and Vascular Research, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, Københavns Universitet5 Department of Chemistry, Faculty of Science, Københavns Universitet
Coherent glycolytic oscillations in Saccharomyces cerevisiae are a multicellular property induced by addition of glucose to a starved cell population of sufficient density. However, initiation of oscillations requires an additional perturbation, usually addition of cyanide. The fate of cyanide during glycolytic oscillations has not previously been studied, and is the subject of the present paper. Using a cyanide electrode, a substantial decrease in cyanide concentration was observed. In the pH range 6-7, we found experimentally that the electrode behaves reasonably well, provided changes in pH are taken into account. To our knowledge, use of a cyanide electrode to study cyanide dynamics in living biological systems is new. Cyanide was found to enter starving yeast cells in only negligible amounts, and did not react significantly with glucose. Thus, cyanide consumption must be explained by reactions with glycolytic intermediates and evaporation. Evaporation and reaction with the signalling substance, extracellular acetaldehyde (ACA(x)) only explains the observed cyanide removal if [ACA(x)] is improbably high. Furthermore, differences in NADH traces upon cyanide addition before or after glucose addition strongly suggest that cyanide also reacts with intracellular carbonyl-containing metabolites. We show that cyanide reacts with pyruvate (Pyr) and dihydroxyacetone phosphate in addition to ACA, and estimate their rate constants. Our results strongly suggest that the major routes of cyanide removal during glycolysis are reactions with pyruvate and ACA. Cyanide removal by all carbonyl-containing intermediates led to a lower mean [ACA(x) ], thereby increasing the amplitude of [ACA(x) ] oscillations.
F E B S Journal (online), 2012, Vol 279, Issue 23, p. 4410-4420