title: Mechanistic studies of reactions of peroxodiiron(III) intermediates in T201 variants of toluene/o-xylene monooxygenase hydroxylase.
abstract: Site-directed mutagenesis studies of a strictly conserved T201 residue in the active site of toluene/o-xylene monooxygenase hydroxylase (ToMOH) revealed that a single mutation can facilitate kinetic isolation of two distinctive peroxodiiron(III) species, designated T201(peroxo) and ToMOH(peroxo), during dioxygen activation. Previously, we characterized both oxygenated intermediates by UV-vis and Mössbauer spectroscopy, proposed structures from DFT and QM/MM computational studies, and elucidated chemical steps involved in dioxygen activation through the kinetic studies of T201(peroxo) formation. In this study, we investigate the kinetics of T201(peroxo) decay to explore the reaction mechanism of the oxygenated intermediates following O(2) activation. The decay rates of T201(peroxo) were monitored in the absence and presence of external (phenol) or internal (tryptophan residue in an I100W variant) substrates under pre-steady-state conditions. Three possible reaction models for the formation and decay of T201(peroxo) were evaluated, and the results demonstrate that this species is on the pathway of arene oxidation and appears to be in equilibrium with ToMOH(peroxo).
authors: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors: Woon Ju
authors: WJ
authors: Song
authors: Stephen J
authors: SJ
authors: Lippard
references: Eur J Biochem. 2002 Nov;269(22):5689-99
references: 12423369
references: Chem Rev. 1996 Nov 7;96(7):2625-2658
references: 11848839
references: Proc Natl Acad Sci U S A. 2010 Sep 7;107(36):15722-7
references: 20798054
references: Biochemistry. 2006 May 2;45(17):5393-401
references: 16634620
references: Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):3784-9
references: 12640145
references: J Am Chem Soc. 2009 May 6;131(17):6074-5
references: 19354250
references: FEMS Microbiol Rev. 2003 Oct;27(4):449-79
references: 14550940
references: Biochemistry. 2011 Mar 22;50(11):1788-98
references: 21366224
references: Biochemistry. 2010 Sep 14;49(36):7902-12
references: 20681546
references: Proc Natl Acad Sci U S A. 2009 Sep 1;106(35):14814-9
references: 19706422
references: J Am Chem Soc. 2010 Oct 6;132(39):13582-5
references: 20839885
references: J Am Chem Soc. 2011 May 18;133(19):7384-97
references: 21517016
references: J Am Chem Soc. 2002 Dec 11;124(49):14608-15
references: 12465971
references: J Am Chem Soc. 2007 Nov 21;129(46):14500-10
references: 17967027
references: Proc Natl Acad Sci U S A. 2011 Sep 6;108(36):14795-800
references: 21859951
references: J Am Chem Soc. 2006 Jun 14;128(23):7458-9
references: 16756297
references: Biochemistry. 2009 May 12;48(18):3838-46
references: 19290655
references: Biochemistry. 1998 Jun 30;37(26):9211-9
references: 9649301
references: Chem Rev. 2000 Jan 12;100(1):235-350
references: 11749238
references: Proc Natl Acad Sci U S A. 2008 May 13;105(19):6858-63
references: 18458342
references: Biochemistry. 1999 Apr 6;38(14):4423-32
references: 10194363
references: Biochemistry. 2010 Nov 16;49(45):9679-81
references: 20923139
references: Science. 1997 Jan 24;275(5299):515-8
references: 8999792
references: J Mol Evol. 2003 Apr;56(4):435-45
references: 12664163
references: Biochemistry. 2000 Nov 7;39(44):13503-15
references: 11063587
references: J Biol Chem. 2004 Jul 16;279(29):30600-10
references: 15096510
references: J Mol Biol. 1993 Jul 5;232(1):123-64
references: 8331655
references: Angew Chem Int Ed Engl. 2001 Aug 3;40(15):2782-2807
references: 29711993
references: J Am Chem Soc. 2009 Sep 30;131(38):13608-9
references: 19731912
references: Biochemistry. 2009 Dec 29;48(51):12145-58
references: 19921958
references: Proc Natl Acad Sci U S A. 1993 Mar 15;90(6):2486-90
references: 8460163
references: Biochemistry. 2007 Dec 25;46(51):14795-809
references: 18044971
references: Proc Natl Acad Sci U S A. 2008 Dec 9;105(49):19194-8
references: 19033467
references: J Am Chem Soc. 2005 May 25;127(20):7370-8
references: 15898785
references: Chem Rev. 2004 Sep;104(9):3947-80
references: 15352783