title: Platinum nanoparticles have an activity similar to mitochondrial NADH:ubiquinone oxidoreductase.
abstract: This study was designed to examine if platinum nanoparticles have an activity similar to mitochondrial complex I, NADH:ubiquinone oxidoreductase. Platinum nanoparticles were prepared by a citrate reduction of H(2)PtCl(6) and protected by citrate itself and pectin (CP-Pt). Time- and dose-dependent decreases in NADH and a time-dependent increase in NAD(+) were observed in the presence of 50 microM CP-Pt; these observations were made using a spectrophotometric method in which the maximum absorption spectra at 340 and 260 nm were used for NADH and NAD(+), respectively. The required platinum concentration in CP-Pt to achieve a 50% oxidation of NADH for 3h was approximately 20 microM, and this NADH oxidation did not require oxygen as an electron acceptor. We also verified NAD(+) formation using an NAD(+)/NADH quantification kit. The absorption peak shift from 278 to 284 nm of 2,3-dimethoxy-5-methyl-6-(3-methyl-2-butenyl)-1,4-benzoquinone (CoQ(1)) was observed by incubating CoQ(1) with CP-Pt in an aqueous buffer. A further analysis with HPLC revealed the reduction of CoQ(1) to CoQ(1)H(2) by CP-Pt. As a whole, platinum nanoparticles have an NADH:ubiquinone oxidoreductase-like activity. This suggests that platinum nanoparticles are a potential medicinal substance for oxidative stress diseases with suppressed mitochondrial complex I.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hikosaka
authors.forename: Juewon
authors.initials: J
authors.lastname: Kim
authors.forename: Masashi
authors.initials: M
authors.lastname: Kajita
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Kanayama
authors.forename: Yusei
authors.initials: Y
authors.lastname: Miyamoto
mesh_terms: D019343:Citric Acid / Q000737:chemistry; D042967:Electron Transport Complex I / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008929:Mitochondria, Heart / Q000201:enzymology*; D010084:Oxidation-Reduction; D010368:Pectins / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties; D014451:Ubiquinone / Q000737:chemistry*
chemical_list: D014451:Ubiquinone; D019343:Citric Acid; D010984:Platinum; D010368:Pectins; D042967:Electron Transport Complex I; C025203:Ubiquinone Q1