The Structure of Chicken Liver Xanthine Dehydrogenase

Sato, Atsushi; Nishino, Tokuzo; Noda, Kôichi; Amaya, Yoshihiro

doi:10.1074/jbc.270.6.2818

Cited by 78 publications

(59 citation statements)

References 31 publications

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“…By this criterion, the rat AOXs clearly belong to the molybdenum iron-sulfur flavoproteins that include AOX, XDH, and XO. Furthermore, the rat AOXs conform to the domain models proposed for XDHs (7,30,31). Amino acids critical for catalysis of this class of enzymes are conserved in the rat AOX sequences as they are in most other AOXs and XDHs.…”

Section: Discussionmentioning

confidence: 96%

cDNA Cloning, Sequencing, and Characterization of Male and Female Rat Liver Aldehyde Oxidase (rAOX1)

Wright

Clayton

Riley

et al. 1999

Journal of Biological Chemistry

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Molecular characterization of male and female rat liver aldehyde oxidase is reported. As described for the mouse liver, male and female rat liver expressed kinetically distinct forms of aldehyde oxidase. Our data suggest that the two forms arise as a result of differences in redox state and are most simply explained by expression of a single gene encoding aldehyde oxidase in rats. In support of this argument we have sequenced cDNAs from male and female rat liver. We examined mRNA expression by Northern blot analysis with RNA from males and females, from several tissues, and following androgen induction. Purified rat liver enzyme from males or females revealed a single 150-kDa species consistent with cDNA sequence analysis. Both male and female forms were reactive to the same carboxyl-terminal directed antisera. K m(app) values obtained in crude extracts of male or female rat liver and post-benzamidine-purified aldehyde oxidase differed substantially from each other but could be interconverted by chemical reduction with dithiothreitol or oxidation with 4,4-dithiodipyridine. Our data indicate that a single gene is most likely expressed in male or female rat liver and that the kinetic differences between male and female rat liver aldehyde oxidases are sensitive to redox manipulation. Aldehyde oxidase (AOX)1 is a member of the molybdenum cofactor containing enzymes. Native AOX is routinely prepared as a homodimer of 300 kDa. Each 150-kDa subunit contains two iron-sulfur centers, an FAD, and the molybdenum-pterin cofactor (MoCo) (1-3). AOX (EC 1.2.3.1) catalyzes the oxidation of a wide range of aldehydic compounds, purines, quinoliniums, and numerous pharmacologic agents. While substrate specificity for AOX is very broad, and wide species variation in substrate specificity exists, the general catalytic reaction takes the form of hydroxyl transfer from water to an aldehyde creating the cognate acid. For example, conversion of benzaldehyde to benzoic acid is a very efficient reaction for AOX from most species. Conversion of N-1-methyl nicotinamide (NMN) to the 2-or -4-pyridone has been used as a standard definition of AOXs, although it is usually a kinetically less efficient reaction than benzaldehyde oxidation.AOX is of interest both for its role in drug metabolism and as a source of the reactive oxygen species (ROS), hydrogen peroxide, and the superoxide anion, that have been related to numerous human pathologies. The human gene encoding AOX has been linked to a rare form of amyotrophic lateral sclerosis, although it is unknown if AOX encodes the amyotrophic lateral sclerosis locus itself (4 -6). ROS are generated from AOX in an oxidative half-reaction following reduction of the enzyme by substrate. The FeS, FAD, and MoCo cofactors comprise an internal electron transfer chain in which electrons are passed from the active site molybdenum center to the FeS centers and finally to FAD. Partial reduction of oxygen at the the reduced FAD site produces ROS. Unlike the related enzyme xanthine dehydrogenase (XDH), AOX does no...

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Section: Discussionmentioning

confidence: 96%

cDNA Cloning, Sequencing, and Characterization of Male and Female Rat Liver Aldehyde Oxidase (rAOX1)

Wright

Clayton

Riley

et al. 1999

Journal of Biological Chemistry

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“…To test the potential involvement of these residues, we constructed two further mutants, C535A/C992R/C1316S and C535A/ C992R/C1324S. In the chicken enzyme, the residue Cys 1324 is replaced by phenylalanine, whereas the residue Cys 1316 is conserved (27).…”

Section: Reduction Of C535a/c992r Mutants Having Various Levels Of Oxmentioning

confidence: 99%

“…To confirm the role of these residues, we constructed three mutants of rat XOR, C535A, C992R, and C535A/ C992R. In the chicken enzyme, which cannot be converted to XO by any treatment, the residue Cys 992 is replaced by an arginine, whereas the residue Cys 535 is conserved (27). The soluble form of recombinant rat liver XOR was expressed in the baculovirus/Sf9 cell system (20).…”

Section: Expression and Purification Of Three Mutants Of Rat Livermentioning

confidence: 99%

Mechanism of the Conversion of Xanthine Dehydrogenase to Xanthine Oxidase

Nishino

Okamoto

Kawaguchi

et al. 2005

Journal of Biological Chemistry

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142

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Mammalian xanthine dehydrogenase can be converted to xanthine oxidase by modification of cysteine residues or by proteolysis of the enzyme polypeptide chain. Here we present evidence that the Cys 535 and Cys 992 residues of rat liver enzyme are indeed involved in the rapid conversion from the dehydrogenase to the oxidase. The purified mutants C535A and/or C992R were significantly resistant to conversion by incubation with 4,4-dithiodipyridine, whereas the recombinant wildtype enzyme converted readily to the oxidase type, indicating that these residues are responsible for the rapid conversion. The C535A/C992R mutant, however, converted very slowly during prolonged incubation with 4,4-dithiodipyridine, and this slow conversion was blocked by the addition of NADH, suggesting that another cysteine couple located near the NAD ؉ binding site is responsible for the slower conversion. On the other hand, the C535A/C992R/C1316S and C535A/C992R/ C1324S mutants were completely resistant to conversion, even on prolonged incubation with 4,4-dithiodipyridine, indicating that Cys 1316 and Cys 1324 are responsible for the slow conversion. The crystal structure of the C535A/ C992R/C1324S mutant was determined in its demolybdo form, confirming its dehydrogenase conformation.

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“…Conversion of XDH into XO is a not a general characteristic of all eukaryotic XORs, e.g. chicken liver XOR is present only in the XDH form and does not undergo conversion into XO [2].…”

mentioning

confidence: 99%

Characterization of superoxide production from aldehyde oxidase: An important source of oxidants in biological tissues

Kundu

Hille

Murugesan

et al. 2007

Archives of Biochemistry and Biophysics

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Aldehyde oxidase, a molybdoflavoenzyme that plays an important role in aldehyde biotransformation, requires oxygen as substrate and produces reduced oxygen species. However, little information is available regarding its importance in cellular redox stress. Therefore, studies were undertaken to characterize its superoxide and hydrogen peroxide production. Aldehyde oxidase was purified to >98% purity and exhibited a single band at ∼290 kDa on native polyacrylamide gradient gel electrophoresis. Superoxide generation was measured and quantitated by cytochrome c reduction and EPR spin trapping with p-dimethyl aminocinnamaldehyde as reducing substrate. Prominent superoxide generation was observed with an initial rate of 295 nmol/min/mg. Electrochemical measurements of oxygen consumption and hydrogen peroxide formation yielded values of 650 nmol/min/mg and 355 nmol/min/mg. In view of the ubiquitous distribution of aldehydes in tissues, aldehyde oxidase can be an important basal source of superoxide that would be enhanced in disease settings where cellular aldehyde levels are increased. KeywordsAldehyde oxidase; Xanthine oxidase; Superoxide; Hydrogen peroxide; Electron paramagnetic resonance; Spin trapping; Cytochrome c reduction; Reactive oxygen species; Free radicals; Oxygen consumption Aldehyde oxidase (AO; EC 1.2.3.1) 1 is a prominent member of the molybdenum hydroxylase family of enzymes, which also includes xanthine oxidoreductase (XOR). XOR has two interconvertible forms, xanthine dehydrogenase (XDH; EC 1.1.1.204) and xanthine oxidase (XO; 1. 1.3.22). Both forms of XOR are involved in the catabolism of purines, * To whom correspondence should be addressed: Davis Heart and Lung Research Institute, 473 W. 12th Ave, Room 110G, The Ohio State University, Columbus, OH 43210. Phone: (614) . E-Mail: Jay.Zweier@osumc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Both XOR and AO are homodimeric consisting of two identical subunits with an approximate molecular mass of 145 kDa each. Each subunit consists of four discrete regions -two N-terminal domains contain distinct [2Fe-2S] centers. A linker peptide connects it to a 40 kDa FAD binding domain that positions the flavin ring in close proximity and a second linker peptide connects the FAD domain with the 85 kDa C-terminal portion of the protein that contains the molybdenum center and the substrate binding pocket [3,4]. The structure of XOR is well conserved among human, chicken, mouse and rat enzymes [5] and the amino acid sequences reveal that the molybdenum binding site is the most conserved region with 94% homo...

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The Structure of Chicken Liver Xanthine Dehydrogenase

Cited by 78 publications

References 31 publications

cDNA Cloning, Sequencing, and Characterization of Male and Female Rat Liver Aldehyde Oxidase (rAOX1)

cDNA Cloning, Sequencing, and Characterization of Male and Female Rat Liver Aldehyde Oxidase (rAOX1)

Mechanism of the Conversion of Xanthine Dehydrogenase to Xanthine Oxidase

Characterization of superoxide production from aldehyde oxidase: An important source of oxidants in biological tissues

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