Bisphosphoglycerate mutase (BPGM) is an enzyme unique to erythrocytes and placental cells. It is responsible for the catalytic synthesis of 2,3-Bisphosphoglycerate (2,3-BPG) from 1,3-bisphosphoglycerate. BPGM also has a mutase and a phosphatase function, but these are much less active, in contrast to its glycolitic cousin, phosphoglycerate mutase (PGM), which favors these two functions, but can also catalyze the synthesis of 2,3-BPG to a lesser extent.

Because the main function of bisphosphoglycerate mutase is the synthesis of 2,3-BPG, this enzyme is found only in erythrocytes and placental cells. In glycolysis, converting 1,3-BPG to 2,3-BPG would be very inefficient, as it just adds another unnecessary step. Since the main role of 2,3-BPG is to shift the of hemoglobin toward the deoxy-state, its production is really only useful in the cells which contain hemoglobin- erythrocytes and placental cells.

1,3-BPG is formed as an intermediate in glycolysis. BPGM then takes this and converts it to 2,3-BPG, which serves an important function in oxygen transport. 2,3-BPG binds with high affinity to Hemoglobin, causing a conformational change that results in the release of oxygen. Local tissues can then pick up the free oxygen. This is also important in the placenta, where fetal and maternal blood come within such close proximity. With the placenta producing 2,3-BPG, a large amount of oxygen is released from nearby maternal hemoglobin, which can then dissociate and bind with fetal hemoglobin, which has a much lower affinity for 2,3-BPG.

BPGM is a dimer composed of two identical protein subunits, each with its own active site. Each subunit consists six β-strands, β A-F, and ten α-helices, α 1-10. Dimerization occurs along the faces of β C and α 3 of both monomers. BPGM is roughly 50% identical to its PGM counterpart, with the main active-site residues conserved in nearly all PGMs and BPGMs.

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