Affiliations: Department of Foods and Nutrition, Purdue University,
West Lafayette, IN 47907, USA | Department of Medicinal Chemistry and Molecular
Pharmacology, Purdue University, West Lafayette, IN 47907, USA
Note: [] Address for correspondence: Department of Foods and Nutrition,
Purdue University, Stone Hall, 700 W. State Street, West Lafayette, IN
47907-2059, USA. Fax: +1 765 494 4007; E-mail: [email protected]
Abstract: Our laboratories have described a novel class of ectoproteins at the
cell surface with both NADH or hydroquinone oxidase (NOX) and protein
disulfide-thiol interchange activities (ECTO-NOX proteins). The two activities
exhibited by these proteins alternate to generate characteristic patterns of
oscillations where the period length is independent of temperature. The period
length for the constitutive ECTO-NOX is 24 min. Here we describe a distinctive
age-related ECTO-NOX (arNOX) whose activity is blocked by coenzyme
Q_{10}. arNOX occurs exclusively in aged cells and tissues.
The period length of the oscillations is 26 min. Rather than reducing 1/2
O_{2} to H_{2}O, electrons are
transferred to O_{2} to form superoxide. Superoxide
formation was demonstrated by superoxide dismutase-sensitive reduction of
ferricytochrome c and by reduction of a superoxide-specific tetrazolium salt.
Quinone inhibition was given by coenzymes Q_{8},
_{9} and Q_{10} but not by
Q_{0}, Q_{2}, Q_{4},
Q_{6} or _{7}. The arNOX provides a
mechanism to propagate reactive oxygen species generated at the cell surface to
surrounding cells and circulating lipoproteins of importance to atherogenesis.
Inhibition of arNOX by dietary coenzyme Q_{10} provides a
rational basis for dietary coenzyme _{10} use to retard
aging-related arterial lesions.
Keywords: NADH (hydroquinone) oxidase, arNOX, coenzyme Q, aging, superoxide, atherogenesis
Journal: BioFactors, vol. 18, no. 1-4, pp. 33-43, 2003
