2.3- Bisphosphoglycerate glycolysis

In erythrocytes, the first site in glycolysis for generation of ATP may be bypassed, leading to the formation of 2,3-bisphosphoglycerate, which is important in decreasing the affinity of hemoglobin for Oj. 

Production of 2,3-bisphosphoglycerate, by reactions closely associated with glycolysis, is important in regulating the ability of Hb to transport oxygen. 

For each molecule of glucose formed from pyruvate, six high-energy phosphate groups are required, four from ATP and two from GTP. In addition, two molecules of NADH are required for the reduction of two molecules of 1,3-bisphosphoglycerate. Clearly, Equation 14-9 is not simply the reverse of the equation for conversion of glucose to pyruvate by glycolysis, which requires only two molecules of ATP ... 

In glycolysis, ADP is phosphorylated to ATP during the oxidation of glyceraldehyde 3-phosphate to 3-phosphoglycerate. The phosphorylated intermediate that receives the energy of the oxidation is 1,3-bisphosphoglycerate. 

During glycolysis, glyceraldehyde 3-phosphate is converted to 1,3-bisphosphoglycerate and the equilibrium of the adenylate kinase reaction lies in favor of 3-phosphoglycerate, so the metabolites are drawn through the pathway of reactions. 

Glycolysis proceeds in the presence of arsenate, but the ATP normally formed in the conversion of 1,3-bisphosphoglycerate into 3-phosphoglycerate is lost. Thus, arsenate uncouples oxidation and phosphorylation by forming a highly labile acyl arsenate. 

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