mannose-6-phosphate isomerase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: D-mannose 6-phosphate = D-fructose 6-phosphate. [EC:5.3.1.8]

Mannose-6-phosphate isomerase (MPI) activity catalyzes the reversible isomerization of mannose-6-phosphate (M6P) to fructose-6-phosphate (F6P). This reaction is crucial in carbohydrate metabolism, particularly in the hexose monophosphate shunt (HMS), also known as the pentose phosphate pathway. MPI plays a key role in the interconversion of glucose and fructose, and it is essential for the synthesis of various important biomolecules.

**Detailed Molecular Function:**

1. **Metabolic Interconversion:** MPI facilitates the conversion of M6P, a product of the phosphorylation of mannose, to F6P, a crucial intermediate in glycolysis and the HMS. This interconversion is reversible, allowing for flexibility in metabolic pathways.

2. **Hexose Monophosphate Shunt (HMS):** MPI is a key enzyme in the oxidative branch of the HMS. This pathway provides reducing power in the form of NADPH, essential for biosynthesis processes like fatty acid and steroid synthesis, and it also generates the precursor for nucleotide biosynthesis, ribose-5-phosphate.

3. **Glycolysis:** While MPI is not directly involved in the main glycolytic pathway, its role in providing F6P contributes to the overall flow of carbon through glycolysis, ultimately producing ATP.

4. **Regulation of Glucose Metabolism:** MPI activity is influenced by factors such as substrate availability and regulatory enzymes. This regulation ensures efficient use of glucose for energy production and biosynthetic processes.

5. **Nucleotide Biosynthesis:** Through its role in the HMS, MPI indirectly contributes to the biosynthesis of nucleotides, essential for DNA and RNA synthesis.

**Overall, mannose-6-phosphate isomerase activity plays a central role in carbohydrate metabolism by enabling the interconversion of glucose and fructose, contributing to the HMS for biosynthesis, and indirectly influencing glycolysis and nucleotide biosynthesis.**
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Proteins (2)

Compounds (10)