C6H13O9P

C6H13O9P is the empirical formula for glucose-6-phosphate (G6P), a phosphorylated derivative of glucose and a central metabolite in cellular energy pathways. It is the phosphate ester of D-glucose, with a phosphate group attached to the primary hydroxyl at carbon 6.

G6P is a highly polar, water-soluble molecule. At physiological pH, the phosphate group is largely deprotonated, giving the molecule a negative charge that influences its cellular transport and enzyme interactions.

Biosynthesis and metabolic fate: Glucose is phosphorylated by hexokinase or glucokinase, using ATP, to form G6P. From there, it can be isomerized to fructose-6-phosphate by phosphoglucose isomerase and enter glycolysis. Alternatively, G6P can be converted to glucose-1-phosphate by phosphoglucomutase, feeding glycogen synthesis, or diverted into the pentose phosphate pathway via glucose-6-phosphate dehydrogenase.

Physiological role: G6P acts as a key regulatory and branch-point metabolite linking glycolysis, glycogen metabolism, and the pentose phosphate pathway. Its levels help determine the rate of glucose utilization and storage, and, in liver and kidney, glucose-6-phosphatase can remove the phosphate to release free glucose into the bloodstream during fasting.

See also: glycolysis, gluconeogenesis, pentose phosphate pathway, glycogenesis, hexokinase, glucose-6-phosphatase.