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MetaCyc Enzyme: cyclohexanone monooxygenase

Gene: chnB Accession Number: G-2222 (MetaCyc)

Species: Acinetobacter sp. NCIMB9871

cyclohexanone monooxygenase catalyzes the transformation of cyclohexanone to ε-caprolactone by inserting an oxygen atom into the ring structure.

The enzyme has been isolated and purified 35-fold from Acinetobacter sp. NCIMB9871 and found to be a monomeric flavoprotein, containing one mole of bound FAD per mole protein [Donoghue76]. The enzyme has been extensively studied as a model for Baeyer-Villiger monooxygenases [Ryerson82, Latham86].

The chnB gene encoding the protein has been isolated and overexpressed in Escherichia coli. Initial data suggested that the protein was being expressed efficiently when the fused tac promoter was induced, but was degraded rapidly by the host cell [Chen88]. Improved expression was obtained when the regulatory protein chnR, which is also present on the chn operon, was coexpressed, and when the cells were exposed to cyclohexanone [Iwaki99].

It should be mentioned that a similar protein isolated from a Xanthobacter sp. contained an FMN prosthetic group rather than FAD [Trower89].

Molecular Weight of Polypeptide: 61.0 kD (from nucleotide sequence), 61 kD (experimental) [Iwaki99 ]

Unification Links: ModBase:Q9R2F5 , Protein Model Portal:Q9R2F5 , Swiss-Model:Q9R2F5 , UniProt:Q9R2F5

Relationship Links: Entrez-Nucleotide:PART-OF:AB026669 , Entrez-Nucleotide:RELATED-TO:AB006902 , InterPro:IN-FAMILY:IPR020946 , Pfam:IN-FAMILY:PF00743

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 18-Mar-2004 by Wang A , SRI International
Revised 01-Feb-2007 by Caspi R , SRI International

Enzymatic reaction of: cyclohexanone monooxygenase

Synonyms: cyclohexanone 1,2-monooxygenase, cyclohexanone oxygenase, cyclohexanone,NADPH:oxygen oxidoreductase (lactone-forming)

EC Number:

cyclohexanone + NADPH + H+ + oxygen <=> ε-caprolactone + NADP+ + H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: cyclohexanol degradation

Cofactors or Prosthetic Groups: FAD [Donoghue76]

Kinetic Parameters:

Km (μM)

pH(opt): 9 [Donoghue76]


Chen88: Chen YC, Peoples OP, Walsh CT (1988). "Acinetobacter cyclohexanone monooxygenase: gene cloning and sequence determination." J Bacteriol 170(2);781-9. PMID: 3338974

Donoghue76: Donoghue NA, Norris DB, Trudgill PW (1976). "The purification and properties of cyclohexanone oxygenase from Nocardia globerula CL1 and Acinetobacter NCIB 9871." Eur J Biochem 63(1);175-92. PMID: 1261545

Iwaki99: Iwaki H, Hasegawa Y, Teraoka M, Tokuyama T, Bergeron H, Lau PC (1999). "Identification of a transcriptional activator (ChnR) and a 6-oxohexanoate dehydrogenase (ChnE) in the cyclohexanol catabolic pathway in Acinetobacter sp. Strain NCIMB 9871 and localization of the genes that encode them." Appl Environ Microbiol 65(11);5158-62. PMID: 10543838

Latham86: Latham J, Walsh C (1986). "Bacterial cyclohexanone oxygenase. A versatile flavoprotein oxygen transfer catalyst." Ann N Y Acad Sci 471;208-16. PMID: 3460495

Ryerson82: Ryerson CC, Ballou DP, Walsh C (1982). "Mechanistic studies on cyclohexanone oxygenase." Biochemistry 21(11);2644-55. PMID: 7093214

Trower89: Trower MK, Buckland RM, Griffin M (1989). "Characterization of an FMN-containing cyclohexanone monooxygenase from a cyclohexane-grown Xanthobacter sp." Eur J Biochem 181(1);199-206. PMID: 2540966

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Mon Aug 31, 2015, biocyc13.