Transfer of NADH from glycolysis into the mitochondria

Malate Aspartate Glycolysis

The mitochondrial inner membrane is impermeable to NAD, and therefore the NADH produced in the cytosol in glycolysis cannot enter the mitochondria for reoxidation. In order to transfer the reducing equivalents from cytosolic NADH into the mitochondria, two substrate shuttles are used The malate aspartate shuttle Figure 5.11 involves reduction of oxaloacetate in the cytosol to malate with the oxidation of cytosolic NADH to NAD . Malate enters the mitochondria and is reduced back to oxaloacetate,...

Hormonal control in the fed and fasting states

Hydrolysis Triacylglycerol

In the fed state see Figure 5.6 , when there is an ample supply of metabolic fuels from the gut, the main processes occurring are synthesis of reserves of triacylglycerol and glycogen glucose is in plentiful supply and is the main fuel for most tissues. By contrast, in the fasting state see Figure 5.7 the reserves of triacylglycerol and glycogen are mobilized for use, and glucose, which is now scarce, must be spared for use by the brain and red blood cells. As discussed in section 5.3, the...

The pentose phosphate pathway in red blood cells favism

Pathway Production Red Blood Cells

The pentose phosphate pathway is also important in the red blood cell, where NADPH is required to maintain an adequate pool of reduced glutathione, which is used to remove hydrogen peroxide. As shown in Figure 5.15, the tripeptide glutathione y-glutamyl-cysteinyl-glycine is the reducing agent for glutathione peroxidase, which reduces H2O2 to H2O and O2. Glutathione peroxidase is a selenium-dependent enzyme section 11.15.2.5 , and this explains the antioxidant action of selenium. Oxidized...

Oxidation of acetyl CoA THE citric acid CYCLE

Citric Acid Cycle With Compounds

The acetate of acetyl CoA undergoes a stepwise oxidation to carbon dioxide and water in a cyclic pathway, the citric acid cycle, shown in Figures 5.17 and 5.18. This pathway is sometimes known as the Krebs cycle, after its discoverer, Sir Hans Krebs. For each mole of acetyl CoA oxidized in this pathway, there is a yield of Figure 5.17 An overview of the citric acid cycle also known as the Krebs cycle or tricarboxylic acid cycle . Figure 5.17 An overview of the citric acid cycle also known as...