Foszfoglukókináz

Foszfoglukókináz is an enzyme that plays a crucial role in carbohydrate metabolism, specifically in the synthesis of glycogen. It is also known as phosphoglucomutase. This enzyme catalyzes the reversible conversion of glucose-1-phosphate to glucose-6-phosphate. This interconversion is a key step in both glycogenolysis (the breakdown of glycogen) and glycogenesis (the synthesis of glycogen).

In glycogenolysis, glucose-1-phosphate is released from glycogen. Foszfoglukókináz then transforms this into glucose-6-phosphate, which can enter glycolysis for energy production or be converted back to glucose in the liver. In glycogenesis, glucose-6-phosphate, which is abundant after a meal, is converted by foszfoglukókináz to glucose-1-phosphate. This glucose-1-phosphate is then activated by UDP-glucose pyrophosphorylase to form UDP-glucose, the direct precursor for glycogen synthesis.

The enzyme requires glucose-1,6-bisphosphate as a cofactor. The reaction is a phosphoryl group transfer, where the phosphoryl group from glucose-1,6-bisphosphate is transiently transferred to the enzyme's active site before being transferred to glucose-6-phosphate. This enzyme is found in most tissues, with particularly high activity in the liver and muscles, reflecting their central roles in glucose homeostasis and energy storage.