Phosphorylation means utilisation of ATP. Fructose-6-phosphate is phosphorylated (converted) to Fructose-1,6-bisphosphate in the presence of phosphofructokinase by using ATP.

Phosphorylation in Glycolysis

In glycolysis, a series of enzymatic reactions occur to breakdown glucose into pyruvate, producing energy in the form of ATP. One of the key steps in glycolysis is the phosphorylation of glucose, which involves the addition of a phosphate group to glucose. This process is catalyzed by the enzyme hexokinase.

Formation of Fructose-1,6-bisphosphate

During the early stages of glycolysis, glucose is phosphorylated to form glucose-6-phosphate. This phosphorylated glucose molecule is then converted into fructose-6-phosphate by the enzyme phosphoglucose isomerase. The next step involves the phosphorylation of fructose-6-phosphate by the enzyme phosphofructokinase-1 (PFK-1), resulting in the formation of fructose-1,6-bisphosphate.

Regulation and Significance

The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate is an important regulatory step in glycolysis. Phosphofructokinase-1, the enzyme responsible for this phosphorylation, is a key regulatory enzyme that controls the rate of glycolysis. It is allosterically regulated by various factors such as ATP, ADP, citrate, and fructose-2,6-bisphosphate.

This phosphorylation step is important for several reasons:

1. Activation of Fructose-1,6-bisphosphate: Fructose-1,6-bisphosphate is a highly reactive molecule that can be readily cleaved into two three-carbon molecules, dihydroxyacetone phosphate (DHAP) and 3-glyceraldehyde phosphate (GAP). These two molecules then continue through the rest of the glycolytic pathway.

2. Commitment to Glycolysis: The formation of fructose-1,6-bisphosphate is an irreversible step, committing glucose to enter the glycolytic pathway. It ensures that glucose is efficiently utilized for energy production rather than being diverted into alternative metabolic pathways.

3. Energy Production: Each phosphorylation step in glycolysis results in the production of ATP. The conversion of fructose-6-phosphate to fructose-1,6-bisphosphate is an ATP-consuming step and contributes to the overall ATP production during glycolysis.

In conclusion, fructose-1,6-bisphosphate is formed through phosphorylation in glycolysis. This process is catalyzed by the enzyme phosphofructokinase-1 and is crucial for the regulation and efficient utilization of glucose in energy production.