Gluconeogenesis Definition Non Carbohydrate Glucose Site Liver 80

Gluconeogenesis Definition : Non Carbohydrate Glucose § Site : Liver (80%), Kidney 20%) ? Small Intestine Why Glucose is very important! • Brain always requires glucose • In muscle as substrate for ATP production without oxygen • Erythrocyte use only glucose for energy production • Mammary gland lactose Gluconeogenesis : For lactate clearance In Ruminant propionic acid is substrate for gluconeogenesis §

§ § Lactic Acid Glucose The path : TCA Cycle and reversal of glycolysis with four additional enzymes: Pyruvate Carboxylase PEP Carboxykinase F 1, 6 BPase G 6 Pase Glycerol Glucose Glycerol from lipolysis ( break down of Triglyceride) taken up by the liver Glycogenic amino acids glucose

PEP

ATP HCO 3 - Mg++ ADP + Pi

PEP Carboxykinase Human, cow and guinea pig, in the mitochondria and in the cytoplasm l In rats only in the mitochondrions l In birds and marmots only in the mitochondrion Malate and PEP in human exit from the mitochondrion In rats malate transported out of the mitochondrion and converted to oxaloacetate l

Gluconeogenesis and Glycolysis are reciprocally regulated • Fructose 1, 6 -bisphosphatase is main regulatory step in gluconeogenesis. • Corresponding step in glycolysis is 6 -phosphofructo-1 -kinase (PFK-1). • These two enzymes are regulated in a reciprocal manner by several metabolites. Fructose-6 -phosphate + Citrate AMP + 6 -phosphofructo -1 -kinase Fructose 1, 6 -bisphosphatase - AMP - F 2, 6 -BP + Fructose 1, 6 -bisphosphate Reciprocal control—prevents simultaneous reactions in same cell.

Propionate Glucose

Ala Cys Gly Ser Thr Trp Fates of Amino Acid degradation products Glucose Pyruvate Phosphoenolpyruvate Asn Asp Leu Lys Ile Acetyl Co. A Acetoacetate Citrate Oxaloacetate Isocitrate Citric Acid Cycle Malate Phe Tyr a-Ketoglutarate Fumarate Glucogenic Ketogenic Both Glucogenic & Ketogenic Succinate Phe Trp Tyr Succinyl Co. A Gln Glu Ile Met Thr Val Arg His Pro