IntEnz

EC 1.14.13.81 - Magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase

IntEnz Enzyme Nomenclature
EC 1.14.13.81

Names

Reactions

• (1) magnesium-protoporphyrin IX 13-monomethyl ester + 3 NADPH + 3 H+ + 3 O2 = 3,8-divinyl protochlorophyllide + 3 NADP+ + 5 H2O
•   (1a) magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H+ + O2 = 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + NADP+ + H2O
•   (1b) 131-hydroxy-magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H+ + O2 = 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + NADP+ + 2 H2O
•   (1c) 131-oxo-magnesium-protoporphyrin IX 13-monomethyl ester + NADPH + H+ + O2 = 3,8-divinyl protochlorophyllide a + NADP+ + 2 H2O

Cofactor

• Fe cation

Comments:

Requires Fe(II) for activity. The enzyme participates in the biosynthesis of chlorophyllide a in aerobic organisms. The same transformation is achieved in anaerobic organisms by EC 1.21.98.3, anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase. Some facultative phototrophic bacteria, such as Rubrivivax gelatinosus, possess both enzymes.

Links to other databases

References

1. Walker, C. J., Mansfield, K. E., Rezzano, I. N., Hanamoto, C. M., Smith, K. M., Castelfranco, P. A.
   The magnesium-protoporphyrin IX (oxidative) cyclase system. Studies on the mechanism and specificity of the reaction sequence.
   Biochem. J. 255 : 685-692 (1988). [PMID: 3202840]
2. Bollivar, D.W. and Beale, S.I.
   The chlorophyll biosynthetic enzyme Mg-protoporphyrin IX monomethyl ester (oxidative) cyclase (characterization and partial purification from Chlamydomonas reinhardtii and Synechocystis sp. PCC 6803).
   Plant Physiol. 112 : 105-114 (1996). [PMID: 12226378]
3. Pinta, V., Picaud, M., Reiss-Husson, F., Astier, C.
   Rubrivivax gelatinosus acsF (previously orf358) codes for a conserved, putative binuclear-iron-cluster-containing protein involved in aerobic oxidative cyclization of Mg-protoporphyrin IX monomethylester.
   J. Bacteriol. 184 : 746-753 (2002). [PMID: 11790744]
4. Tottey, S., Block, M. A., Allen, M., Westergren, T., Albrieux, C., Scheller, H. V., Merchant, S., Jensen, P. E.
   Arabidopsis CHL27, located in both envelope and thylakoid membranes, is required for the synthesis of protochlorophyllide.
   Proc. Natl. Acad. Sci. U.S.A. 100 : 16119-16124 (2003). [PMID: 14673103]

[EC 1.14.13.81 created 2003, modified 2017]