Lactate, which is produced in the skeletal muscle, is the precursor for gluconeogenesis. In anaerobic conditions, pyruvate is reduced to lactate by using lactate dehydrogenase. Lactate is the end product of glycolysis, since it must be reconverted to pyruvate for its further metabolism. Lactate is carried from the skeletal muscle through blood and handed over…

Glucose 6-phosphatase catalyses the conversion of glucose 6-phosphate to glucose. Figure 8.27 Pathway of Gluconeogenesis and Glycolysis in Liver The presence or absence of this enzyme in a tissue determines whether the tissue is capable of contributing glucose to the blood or not. It is mostly present in liver and kidney but not in muscle, brain,…

Phosphoenol pyruvate undergoes the reversal of glycolysis until fructose 1,6-bisphosphate is produced. The enzyme fructose 1,6-bisphosphatase converts fructose 1,6 bisphosphate to fructose 6-phosphate.

This takes place in two steps. Pyruvate carboxylase is a biotin-dependent mitochondrial enzyme that converts pyruvate to oxaloacetate in the presence of ATP and CO2. This enzyme regulates gluconeogenesis. Oxaloacetate is synthesised in the mitochondrial matrix. It has to be transported to cytosol to be used in gluconeogenesis, where the rest of the pathway occurs.…

Gluconeogenesis closely resembles the reversed pathway of glycolysis, the citric acid cycle, and some special reactions as shown in Figure 8.27. The three stages bypassed by alternate enzymes specific to gluconeogenesis are discussed below: The following are the enzymes involved in gluconeogenesis:

Gluconeogenesis mainly occurs in the cytosol. Gluconeogenesis mostly takes place in the liver and, to some extent, in the kidney matrix;

Gluconeogenesis is the term used to include all pathways responsible for converting all non-carbohydrate precursors to glucose or glycogen. Liver and kidney are the major gluconeogenic tissues. Gluconeogenesis meets the glucose requirement of the body when carbohydrate is not available in the required amount from the diet or from glycogen reserves. Erythrocytes and nervous systems especially require…

INTRODUCTION The synthesis of glucose of glycogen from a non-carbohydrate compounds is known as gluconeogenesis. The major substrates precursors for gluconeogenesis are lactate and pyruvate, glucogenic amino acids, propionate, and glycerol.

The principal products of pentose phosphate pathway are ribose 5-phosphate and NADPH. The transaldolase and transketolase reactions convert excess ribose 5-phosphate to glycolytic intermediates when the metabolic needs for NADPH excess that of ribose 5-phosphate in nucleotide biosynthesis. The resulting gap and fructose 6-phosphate can be consumed through glycolysis and oxidative phosphorylation by gluconeogenesis. Flux…

NADPH is needed for the reductive biosynthesis of fatty acids and steroids, and therefore, HMP occurs more actively in the tissues concerned with lipogenesis, for example, adipose tissue and liver. NADPH is used in the synthesis of amino acids involving the enzyme glutamate dehydrogenase. There is a continuous production of H2O2 in living cells, which is…