Oxidative phosphorylation

1,3-diphosphoglycerate GAP dehydrogenase This is an oxidoreductase reaction in which GAP is oxidized and NAD+ is reduced. The energy obtained from this redox reaction (?G° is about -50 kJ/mole) is enough to attach an inorganic phosphate (not from ATP ***critical***) onto GAP (unfavorable reaction with a ?G° of about +47 kJ/mole). The reaction can be viewed as the sum of two processes: the oxidation of the aldehyde to a carboxylic acid by NAD+, and the joining of the carboxylic acid and inorganic phosphate to form the acyl-phosphate product. The key to this reaction is the formation of a high energy thioester intermediate on the enzyme. See figure 14-9 in book for the enzyme mechanism. ? Must have a supply of NAD+ in cytosol for glycolysis to keep going. ? Under aerobic conditions, the electrons from the NADH produced in this step must be shuttled into the mitochondria using either the malate aspartate shuttle system or the ?-glycerol phosphate shuttle system. The use of the shuttle systems result in NAD+ left in the cytosol and NADH (or FADH2 depending on shuttle) in the mitochondria which enters the electron transport system. ? Under anaerobic conditions, the electron transport system no longer functions; therefore, the pyruvate produced at the end of glycoly