Enzymes are proteins that are essential for the function of all living organisms. They catalyse chemical reactions, thereby accelerating the rate of a reaction without being consumed in the process. In biochemistry, enzymes are of particular importance as they are involved in the metabolism of carbohydrates, fats and proteins. In this review, we will focus on the enzymes involved in glycolysis and gluconeogenesis, two metabolic pathways that involve the breakdown and synthesis of glucose.
Glycolysis is an anaerobic metabolic pathway that is responsible for the breakdown of glucose into pyruvate with the release of energy. It is the first step in the breakdown of carbohydrates and is common to all organisms. The process involves the conversion of a single molecule of glucose into two molecules of pyruvate and the production of ATP, NADH and other energy-rich molecules.
The pathway of glycolysis is divided into two phases: the preparatory phase and the pay-off phase. The preparatory phase consists of the first five enzymes, which catalyse the conversion of glucose into glyceraldehyde 3-phosphate (G3P). These enzymes are hexokinase, phosphoglucose isomerase, phosphofructokinase, aldolase and triose phosphate isomerase.
The pay-off phase consists of the last four enzymes, which catalyse the conversion of G3P into pyruvate with the release of ATP. These enzymes are glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase and pyruvate kinase.
Gluconeogenesis is an anaerobic metabolic pathway responsible for the synthesis of glucose from non-carbohydrate precursors. It is the reverse of glycolysis and is important for maintaining blood glucose levels in the body. The pathway involves the conversion of pyruvate, lactate, glycerol and other non-carbohydrate precursors into glucose.
The enzymes involved in the pathway of gluconeogenesis are similar to those involved in glycolysis. However, the direction of the reaction is reversed and different enzymes are used in some cases. The enzymes involved in gluconeogenesis are phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, glucose 6-phosphatase, pyruvate carboxylase and pyruvate kinase.
Glycolysis and gluconeogenesis are two important metabolic pathways involved in the breakdown and synthesis of glucose. The enzymes involved in these pathways are essential for the function of cells and are essential for the maintenance of blood glucose levels in the body. Understanding the structure and function of these enzymes is essential for a deeper understanding of biochemistry and metabolism.