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EC 1.21.98.3 Details

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EC number

1.21.98.3

Accepted name

anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase

Reaction

magnesium-protoporphyrin IX 13-monomethyl ester + 3 S-adenosyl-L-methionine + H₂O = 3,8-divinyl protochlorophyllide a + 3 5′-deoxyadenosine + 3 L-methionine (overall reaction);;(1a) magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine + H₂O = 13¹-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + 5′-deoxyadenosine + L-methionine;;(1b) 13¹-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 13¹-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + 5′-deoxyadenosine + L-methionine;;(1c) 13¹-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + S-adenosyl-L-methionine = 3,8-divinyl protochlorophyllide a + 5′-deoxyadenosine + L-methionine

Other name(s)

bchE (gene name), MPE cyclase (ambiguous)

Systematic name

magnesium-protoporphyrin-IX 13-monomethyl ester,S-adenosyl-L-methionine:H₂O oxidoreductase (hydroxylating)

Comment

This radical AdoMet enzyme participates in the biosynthesis of chlorophyllide a in anaerobic bacteria, catalysing the formation of an isocyclic ring. Contains a [4Fe-4S] cluster and a cobalamin cofactor. The same transformation is achieved in aerobic organisms by the oxygen-dependent EC 1.14.13.81, magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase. Some facultative phototrophic bacteria, such as Rubrivivax gelatinosus, possess both enzymes.

History

created 2016

EC Tree

1 Oxidoreductases

1.1 Acting on the CH-OH group of donors

1.2 Acting on the aldehyde or oxo group of donors

1.2.1 With NAD⁺ or NADP⁺ as acceptor

1.2.2 With a cytochrome as acceptor

1.2.3 With oxygen as acceptor

1.2.3.1 aldehyde oxidase

1.2.3.2 created 1961, deleted 1984

1.2.3.3 pyruvate oxidase

1.2.3.4 oxalate oxidase

1.2.3.5 glyoxylate oxidase

1.2.3.6 pyruvate oxidase (CoA-acetylating)

1.2.3.7 indole-3-acetaldehyde oxidase

1.2.3.8 pyridoxal oxidase

1.2.3.9 aryl-aldehyde oxidase

1.2.3.10 created 1990, deleted 2003

1.2.3.11 retinal oxidase

1.2.3.12 created 2000, deleted 2003

1.2.3.13 4-hydroxyphenylpyruvate oxidase

1.2.3.14 abscisic-aldehyde oxidase

1.2.3.15 (methyl)glyoxal oxidase

1.2.4 With a disulfide as acceptor

1.2.5 With a quinone or similar compound as acceptor

1.2.7 With an iron-sulfur protein as acceptor

1.2.98 With other, known, physiological acceptors

1.2.99 With unknown physiological acceptors

1.3 Acting on the CH-CH group of donors

1.4 Acting on the CH-NH₂ group of donors

1.5 Acting on the CH-NH group of donors

1.6 Acting on NADH or NADPH

1.7 Acting on other nitrogenous compounds as donors

1.8 Acting on a sulfur group of donors

1.9 Acting on a heme group of donors

1.10 Acting on diphenols and related substances as donors

1.11 Acting on a peroxide as acceptor

1.12 Acting on hydrogen as donor

1.13 Acting on single donors with incorporation of molecular oxygen (oxygenases)

1.14 Acting on paired donors, with incorporation or reduction of molecular oxygen

1.15 Acting on superoxide as acceptor

1.16 Oxidizing metal ions

1.17 Acting on CH or CH₂ groups

1.18 Acting on iron-sulfur proteins as donors

1.19 Acting on reduced flavodoxin as donor

1.20 Acting on phosphorus or arsenic in donors

1.21 Catalysing the reaction X-H + Y-H = X-Y

1.21.1 With NAD⁺ or NADP⁺ as acceptor

1.21.3 With oxygen as acceptor

1.21.4 With a disulfide as acceptor

1.21.98 With other, known, physiological acceptors

1.21.98.1 cyclic dehypoxanthinyl futalosine synthase

1.21.98.2 dichlorochromopyrrolate synthase

1.21.98.3 anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase

1.21.98.4 PqqA peptide cyclase

1.21.99 With unknown physiological acceptors

1.22 Acting on halogen in donors

1.23 Reducing C-O-C group as acceptor

1.97 Other oxidoreductases

1.98 Enzymes using H₂ as reductant (deleted subclass)

1.98.1. undefined

1.99 Other enzymes using O₂ as oxidant (deleted subclass)