Bisphosphoglycerate mutase
- OMIM: 222800
- UniProt: P07738
The Bisphosphoglyceratmutase ( BPGM ), formerly referred to as 2,3- Diphosphoglyceratmutase is an enzyme, especially in the erythrocytes ( red blood cells) present in erythropoetischem tissue of mammals. It is in red blood cells, the central enzyme of the Rapoport - Luebering cycle, a minor route of glycolysis, in which it catalyzes as trifunctional enzyme three different biochemical reactions for the formation and degradation of 2,3- bisphosphoglycerate (2,3- BPG ). 2,3- BPG is as biochemical effector in the regulation of the binding ability ( affinity) of the involved blood pigment hemoglobin for oxygen in RBCs of breathing gas.
Features and Function
The Bisphosphoglyceratmutase catalyzes both as a synthase ( 2,3- DPG synthase synonymous Bisphosphoglyceratmutase, EC 5.4.2.4 ), the formation of 2,3- bisphosphoglycerate (2,3- BPG ) from the resulting 1,3 - bisphosphoglycerate in glycolysis (1,3- BPG ). In addition, it also acts as a phosphatase (2,3- Bisphosphoglyceratphosphatase, EC 3.1.3.13 ) for the reaction of 2,3 -DPG to 3 -phosphoglycerate (3- PG) and a mutase ( Monophosphoglyceratmutase, EC 5.4.2.1 ) for the the equilibrium reaction between the 3- phosphoglycerate - PG compounds and 2 -phosphoglycerate (2- PG).
The BPGM has for the three different functions a common active site, which is equipped with two different binding sites for di- or Monophosphoglycerate. The most important activity of the enzyme is irreversibly running Synthasereaktion, thereby distinguishing it from the phosphoglycerate in the main pathway of glycolysis. This is similar to the BPGM concerning the molecular mass of the subunit structure and amino acid sequence and also acts as a trifunctional enzyme, but with a different ratio of the three activities to each other.
The rearrangement of the neutral material 1,3- DPG to the 2,3 -DPG requires the presence of magnesium ions and has its pH optimum at about 7.2. The hydrolysis of the 2,3-DPG to 3 -PG extends under consumption of a water molecule and release an inorganic phosphate, and runs enhanced at an acidic pH value. The amino acid sequence of human BPGM which has a molar mass of 30,005 daltons and having a homodimeric structure, has a length of 259 amino acids.
Formed in the Rapoport Luebering cycle 2,3-DPG is an important biochemical effector for the regulation of the binding ability ( affinity ) of the blood hemoglobin, the dye for the breathing gas is oxygen. The Bisphosphoglyceratmutase is accordingly mainly in the erythrocytes ( red blood cells) and in erythropoetischem tissue of mammals. Other activities were found beyond including in placental tissue and, to a much lesser extent, in the liver.
Discovery history
The reactions for the formation and cleavage of 2,3- bisphosphoglycerate were discovered by Austrian- German-American biochemist Samuel Mitja Rapoport and his technical assistant Janet Luebering in the 1940s in the United States and described in the early 1950s in several publications. In the 1960s and 1970s, the properties of the enzyme Bisphosphoglyceratmutase and its trifunctional activity were characterized. The amino acid sequence of human BPGM was elucidated in 1983, the nucleotide sequence of the gene in five years later. In 2004, the crystal structure of the enzyme molecule has been published.