This family consists of monooxygenase components such as MmoB methane monooxygenase (EC:1.14.13.25) regulatory protein B. When MmoB is present at low concentration it converts methane monooxygenase from an oxidase to a hydroxylase and stabilises intermediates required for the activation of dioxygen [1]. Also found in this family is DmpM or Phenol hydroxylase (EC:1.14.13.7) protein component P2, this protein lacks redox co-factors and is required for optimal turnover of Phenol hydroxylase [3].

1: Structure of the soluble methane monooxygenase regulatory protein B. Walters KJ, Gassner GT, Lippard SJ, Wagner G; Proc Natl Acad Sci U S A 1999;96:7877-7882. PMID:10393915

2: Solution structure of component B from methane monooxygenase derived through heteronuclear NMR and molecular modeling. Chang SL, Wallar BJ, Lipscomb JD, Mayo KH; Biochemistry 1999;38:5799-5812. PMID:10231531

3: Solution structure of phenol hydroxylase protein component P2 determined by NMR spectroscopy. Qian H, Edlund U, Powlowski J, Shingler V, Sethson I; Biochemistry 1997;36:495-504. PMID:9012665