13bisfosfogliserata

13bisfosfogliserata, also known as 1,3-bisphosphoglycerate (1,3-BPG), is an intermediate compound in the glycolytic pathway, a series of enzymatic reactions that break down glucose to produce energy in the form of adenosine triphosphate (ATP). It plays a crucial role in cellular respiration, particularly in the energy-producing phase of glycolysis known as the payoff phase.

During glycolysis, glucose is phosphorylated and split into two molecules of glyceraldehyde 3-phosphate (G3P). Each G3P molecule undergoes oxidation and phosphorylation in a reaction catalyzed by the enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). This reaction produces 1,3-bisphosphoglycerate, along with nicotinamide adenine dinucleotide (NAD+) being reduced to NADH. The phosphate group added to G3P during this step is derived from inorganic phosphate (Pi) rather than ATP, distinguishing it from earlier phosphorylation steps in glycolysis.

1,3-bisphosphoglycerate is a high-energy molecule due to its two phosphate groups, which are in a high-energy state. It serves as a substrate for the enzyme phosphoglycerate kinase (PGK), which transfers a phosphate group to adenosine diphosphate (ADP), forming ATP and converting 1,3-bisphosphoglycerate into 3-phosphoglycerate. This step is significant because it is one of the primary ways ATP is generated during glycolysis, producing two ATP molecules per glucose molecule (four total, though two are used in earlier steps).

The conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate is an essential step in maintaining the energy balance within cells, ensuring that sufficient ATP is available for cellular processes. Additionally, 1,3-bisphosphoglycerate can also be involved in other metabolic pathways, such as the synthesis of amino acids and nucleotides, though its primary role remains within glycolysis.