Glükóz6foszfat

Glükóz-6-foszfat (G6P) is a phosphorylated derivative of glucose, playing a central role in carbohydrate metabolism and cellular energy regulation. It is formed through the phosphorylation of glucose by the enzyme hexokinase (or glucokinase in certain tissues like the liver) in the presence of adenosine triphosphate (ATP). This reaction occurs during glycolysis, the initial step of glucose breakdown to generate energy in the form of ATP.

Beyond glycolysis, G6P serves as a key substrate in several metabolic pathways. In the liver, it can be converted into glycogen through glycogenesis, a process essential for storing glucose for later use. It also acts as a precursor for the pentose phosphate pathway (PPP), which produces ribose-5-phosphate for nucleotide synthesis and generates NADPH, a reducing agent vital for biosynthetic reactions and antioxidant defense.

G6P is also involved in gluconeogenesis, the synthesis of glucose from non-carbohydrate sources, particularly in the liver and kidneys. The enzyme glucose-6-phosphatase (G6Pase) catalyzes the dephosphorylation of G6P to release free glucose into the bloodstream, maintaining blood sugar levels.

Deficiencies in enzymes involved in G6P metabolism, such as glucose-6-phosphate dehydrogenase (G6PD), can lead to metabolic disorders. G6PD deficiency, for example, impairs the PPP and increases susceptibility to oxidative stress, often resulting in hemolytic anemia under certain conditions.

In summary, glükóz-6-foszfat is a versatile intermediate in cellular metabolism, linking energy production, storage, and biosynthesis while playing a critical role in maintaining glucose homeostasis.