title: Kinetics and regulation of mammalian NADH-ubiquinone oxidoreductase (Complex I).
abstract: NADH-ubiquinone oxidoreductase (Complex I, European Commission No. 1.6.5.3) is one of the respiratory complexes that generate the proton-motive force required for the synthesis of ATP in mitochondria. The catalytic mechanism of Complex I has not been well understood, due to the complicated structure of this enzyme. Here, we develop a kinetic model for Complex I that accounts for electron transfer from NADH to ubiquinone through protein-bound prosthetic groups, which is coupled to the translocation of protons across the inner mitochondrial membrane. The model is derived based on the tri-bi enzyme mechanism combined with a simple model of the conformational changes associated with proton transport. To study the catalytic mechanism, parameter values are estimated by analyzing kinetic data. The model is further validated by independent data sets from additional experiments, effectively explaining the effect of pH on enzyme activity. Results imply that matrix pH significantly affects the enzyme turnover processes. The overall kinetic analysis demonstrates a hybrid ping-pong rapid-equilibrium random bi-bi mechanism, consolidating the characteristics from previously reported kinetic mechanisms and data.
authors.affiliation: Biotechnology and Bioengineering Center and Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Xuewen
authors.initials: X
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Qi
authors.forename: Ranjan K
authors.initials: RK
authors.lastname: Dash
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Beard
mesh_terms: D000818:Animals; D055162:Biocatalysis; D001692:Biological Transport; D002417:Cattle; D042967:Electron Transport Complex I / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008322:Mammals; D008928:Mitochondria / Q000201:enzymology; D051336:Mitochondrial Membranes / Q000378:metabolism; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology; D011522:Protons; D051381:Rats; D015203:Reproducibility of Results
chemical_list: D011522:Protons; D042967:Electron Transport Complex I
references.citation: Proc Natl Acad Sci U S A. 2006 May 16;103(20):7607-12
references.pmid: 16682634
references.citation: J Biol Chem. 1958 Sep;233(3):736-9
references.pmid: 13575447
references.citation: J Bioenerg Biomembr. 1986 Oct;18(5):331-68
references.pmid: 3021714
references.citation: Biochemistry. 1994 Apr 19;33(15):4571-6
references.pmid: 8161512
references.citation: J Bioenerg Biomembr. 2001 Jun;33(3):155-7
references.pmid: 11695824
references.citation: J Am Chem Soc. 2003 May 21;125(20):6020-1
references.pmid: 12785808
references.citation: PLoS Comput Biol. 2005 Sep;1(4):e36
references.pmid: 16163394
references.citation: J Bioenerg Biomembr. 2002 Feb;34(1):11-9
references.pmid: 11860176
references.citation: J Biol Chem. 2004 May 28;279(22):23830-6
references.pmid: 15037611
references.citation: J Neurochem. 2002 Mar;80(5):780-7
references.pmid: 11948241
references.citation: Proc Natl Acad Sci U S A. 2008 Mar 11;105(10):3763-7
references.pmid: 18316732
references.citation: FEBS Lett. 1977 Apr 1;76(1):99-104
references.pmid: 15869
references.citation: Biochemistry. 1996 Feb 27;35(8):2705-16
references.pmid: 8611577
references.citation: Biochim Biophys Acta. 2006 Sep-Oct;1757(9-10):1096-109
references.pmid: 16780790
references.citation: J Biol Chem. 2001 Oct 19;276(42):38345-8
references.pmid: 11522775
references.citation: Annu Rev Biochem. 2006;75:69-92
references.pmid: 16756485
references.citation: Biochem Soc Trans. 2005 Jun;33(Pt 3):525-9
references.pmid: 15916556
references.citation: Biochemistry. 1994 Aug 23;33(33):10069-75
references.pmid: 8060976
references.citation: Biochim Biophys Acta. 2006 May-Jun;1757(5-6):553-61
references.pmid: 16678117
references.citation: Biochim Biophys Acta. 2008 Jul-Aug;1777(7-8):729-34
references.pmid: 18471432
references.citation: FEBS Lett. 2003 Jun 12;545(1):9-17
references.pmid: 12788486
references.citation: Biochem J. 2004 Sep 1;382(Pt 2):511-7
references.pmid: 15175007
references.citation: J Biol Chem. 1969 Nov 10;244(21):5808-19
references.pmid: 5350937
references.citation: Methods Enzymol. 2004;382:3-20
references.pmid: 15047093
references.citation: J Bioenerg Biomembr. 2001 Jun;33(3):169-77
references.pmid: 11695826
references.citation: Arch Biochem Biophys. 1990 Sep;281(2):305-11
references.pmid: 2118334
references.citation: Biochemistry. 2004 Jul 6;43(26):8494-502
references.pmid: 15222760
references.citation: J Bioenerg Biomembr. 2003 Oct;35(5):419-25
references.pmid: 14740890
references.citation: J Biol Chem. 2003 Oct 3;278(40):39155-65
references.pmid: 12871940
references.citation: J Phys Chem B. 2010 Dec 16;114(49):16068-82
references.pmid: 20446702
references.citation: BMC Bioinformatics. 2009 Aug 04;10:238
references.pmid: 19653903
references.citation: Biochim Biophys Acta. 2003 Jul 10;1604(3):135-50
references.pmid: 12837546
references.citation: FEBS Lett. 1993 Oct 11;332(1-2):127-31
references.pmid: 8405427
references.citation: J Mol Biol. 1991 Oct 5;221(3):1027-43
references.pmid: 1834851
references.citation: J Biol Chem. 2007 Aug 24;282(34):24525-37
references.pmid: 17591785
references.citation: FEBS Lett. 2005 Aug 29;579(21):4555-61
references.pmid: 16098512