Glycolysis

About: Glycolysis is a research topic. Over the lifetime, 10593 publications have been published within this topic receiving 507460 citations. The topic is also known as: GO:0006096 & glycolysis.

Involvement of oxygen-sensitive pyruvate formate-lyase in mixed-acid fermentation by Streptococcus mutans under strictly anaerobic conditions.

Abstract: Streptococcus mutans JC2 produced formate, acetate, ethanol, and lactate when suspensions were incubated with an excess of galactose or mannitol under strictly anaerobic conditions. The galactose- or mannitol-grown cell suspensions produced more formate, acetate, and ethanol than the glucose-grown cells even when incubated with glucose. The levels of lactate dehydrogenase and fructose 1,6-bisphosphate were not significantly different in these cells, but the level of pyruvate formate-lyase was higher in the galactose- or mannitol-grown cells, and that of triose phosphate was lower in the galactose-grown cells. This suggests that the regulation of pyruvate formate-lyase may play a major role in the change of the fermentation patterns. The cells of S. mutans grown on glucose produced a significant amount of volatile products even in the presence of excess glucose under strictly anaerobic conditions. However, when the anaerobically grown cells were exposed to air, only lactate was produced from glucose. When cells were anaerobically grown on mannitol and then exposed to air for 2 min, only trace amounts of fermentation products were formed from mannitol under anaerobic conditions. It was found that the pyruvate formate-lyase in the cells was inactivated by exposure of the cells to air.

The Metabolic Significance of the Malate-Aspartate Cycle in Heart.

Abstract: • Under physiological conditions, the energy requirements of the heart are met primarily by the oxidation of fatty acids, glucose, and lactate (1, 2). Initially, during the metabolism of glucose and lactate, the coenzyme NAD is reduced to NADH and pyruvate is formed in the cytosolic compartment of the myocardial cell. Subsequent entry of pyruvate into the mitochondria for oxidative metabolism in the citric acid cycle requires an equivalent oxidation of cytosolic NADH by the mitochondrial electron transport chain, which regenerates NAD. However, direct transfer of the reduced coenzyme NADH to the respiratory chain is prevented by a selective permeability barrier across the inner mitochondrial membrane to NADH as well as other metabolic intermediates (3, 4). Although several indirect shuttle mechanisms have been proposed (5-7), current evidence indicates that the reducing equivalents formed in the reduction of cytosolic NAD to NADH are indirectly carried into the mitochondrial compartment of the heart and other tissues by metabolic anions of the malate-aspartate cycle (8-11). In addition, interaction of the malate-aspartate cycle with the citric acid cycle, through key common metabolic intermediates, may provide a major mechanism by which coordination of mitochondrial and cytosolic energy metabolism is achieved in the myocardium (9, 12, 13).