4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase

In enzymology, a 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase (HMB-PP synthase, IspG, EC 1.17.7.1) is an enzyme that catalyzes the chemical reaction

2-C-methyl-D-erythritol 2,4-cyclodiphosphate + protein-dithiol

\rightleftharpoons

(E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate + H₂O + protein-disulfide

The substrate of this enzyme is 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP) and the product is (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMB-PP). Electrons are donated by two reduced ferredoxin proteins per reaction.

This enzyme belongs to the family of oxidoreductases, specifically those acting on CH or CH₂ groups with a disulfide as acceptor. The systematic name of this enzyme class is (E)-4-hydroxy-3-methylbut-2-en-1-yl-diphosphate:protein-disulfide oxidoreductase (hydrating). This enzyme participates in the MEP pathway (non-mevalonate pathway) of Isoprenoid precursor biosynthesis.

References

D, Rohdich F; Eisenreich, W; Adam, P; Amslinger, S; Kis, K; Bacher, A; Arigoni, D; Rohdich, F (2001). "Studies on the nonmevalonate pathway to terpenes: the role of the GcpE (IspG) protein". Proc. Natl. Acad. Sci. U.S.A. 98 (26): 14837–42. doi:10.1073/pnas.201399298. PMC 64945. PMID 11752431.

Other oxidoreductases (EC 1.15-1.21)

1.15: Acting on superoxide as acceptor	Superoxide dismutase SOD1 SOD2 SOD3

1.16: Oxidizing metal ions	Ceruloplasmin

1.17: Acting on CH or CH2 groups	Xanthine oxidase Ribonucleotide reductase 4-Hydroxy-3-methylbut-2-enyl diphosphate reductase

1.18: Acting on iron-sulfur proteins as donors	Nitrogenase

1.19: Acting on reduced flavodoxin as donor	Nitrogenase (flavodoxin)

1.20: Acting on phosphorus or arsenic in donors	Glutaredoxin GLRX GLRX2 GLRX3 GLRX5

1.21: Acting on X-H and Y-H to form an X-Y bond	Isopenicillin N synthase

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

Metabolism - non-mevalonate pathway enzymes

DXP synthase DXP reductoisomerase 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase 4-(cytidine 5'-diphospho)-2-C-methyl-D-erythritol kinase 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase 4-hydroxy-3-methylbut-2-enyl diphosphate reductase

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