ArticleBiochemistry2010
Effects of interdomain tether length and flexibility on the kinetics of intramolecular electron transfer in human sulfite oxidase.
Article in Biochemistry, 2010. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 21 papers.
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Who cites it
21 citing papers in PubMed, 44 citations in OpenAlex.
- Bringing Nitric Oxide to the Molybdenum World-A Personal Perspective.Molecules (Basel, Switzerland) · 2023Review
- Hydrogen Sulfide Oxidation by Sulfide Quinone Oxidoreductase.Chembiochem : a European journal of chemical biology · 2021Review
- Molybdenum and Tungsten Cofactors and the Reactions They Catalyze.Metal ions in life sciences · 2020Article
- HThe Journal of biological chemistry · 2017Article
- Polymorphic Variants of Human Rhodanese Exhibit Differences in Thermal Stability and Sulfur Transfer Kinetics.The Journal of biological chemistry · 2015Article
- Sulfite Oxidase Catalyzes Single-Electron Transfer at Molybdenum Domain to Reduce Nitrite to Nitric Oxide.Antioxidants & redox signaling · 2015Article
- Sulfite-oxidizing enzymes.Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry · 2015Review
- Nitrite reduction by molybdoenzymes: a new class of nitric oxide-forming nitrite reductases.Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry · 2015Review
- Kinetic results for mutations of conserved residues H304 and R309 of human sulfite oxidase point to mechanistic complexities.Metallomics : integrated biometal science · 2014Article
- Biosynthesis of a central intermediate in hydrogen sulfide metabolism by a novel human sulfurtransferase and its yeast ortholog.Biochemistry · 2014Article
- The mononuclear molybdenum enzymes.Chemical reviews · 2014Review
- Xanthine oxidoreductase-catalyzed reduction of nitrite to nitric oxide: insights regarding where, when and how.Nitric oxide : biology and chemistry · 2013Review
- Probing the role of a conserved salt bridge in the intramolecular electron transfer kinetics of human sulfite oxidase.Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry · 2013Article
- Kinetic and thermodynamic effects of mutations of human sulfite oxidase.Chemistry & biodiversity · 2012Review
- Tyrosine triad at the interface between the Rieske iron-sulfur protein, cytochrome c1 and cytochrome c2 in the bc1 complex of Rhodobacter capsulatus.Biochimica et biophysica acta · 2012Article
- Intramolecular electron transfer in sulfite-oxidizing enzymes: probing the role of aromatic amino acids.Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry · 2012Article
- Determination of the distance between the Mo(V) and Fe(III) heme centers of wild type human sulfite oxidase by pulsed EPR spectroscopy.The journal of physical chemistry. B · 2012Article
- Another look at the interaction between mitochondrial cytochrome c and flavocytochrome b (2).European biophysics journal : EBJ · 2011Review
- Article
- Molybdenum enzymes in higher organisms.Coordination chemistry reviews · 2011Article
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Authors and funding
8 authors at 1 institution in 1 country.
Funding
Abstract
Sulfite oxidase (SO) is a vitally important molybdenum enzyme that catalyzes the oxidation of toxic sulfite to sulfate. The proposed catalytic mechanism of vertebrate SO involves two intramolecular one-electron transfer (IET) steps from the molybdenum cofactor to the iron of the integral b-type heme and two intermolecular one-electron steps to exogenous cytochrome c. In the crystal structure of chicken SO [Kisker, C., et al. (1997) Cell 91, 973-983], which is highly homologous to human SO (HSO), the heme iron and molybdenum centers are separated by 32 A and the domains containing these centers are linked by a flexible polypeptide tether. Conformational changes that bring these two centers into greater proximity have been proposed [Feng, C., et al. (2003) Biochemistry 42, 5816-5821] to explain the relatively rapid IET kinetics, which are much faster than those theoretically predicted from the crystal structure. To explore the proposed role(s) of the tether in facilitating this conformational change, we altered both its length and flexibility in HSO by site-specific mutagenesis, and the reactivities of the resulting variants have been studied using laser flash photolysis and steady-state kinetics assays. Increasing the flexibility of the tether by mutating several conserved proline residues to alanines did not produce a discernible systematic trend in the kinetic parameters, although mutation of one residue (P105) to alanine produced a 3-fold decrease in the IET rate constant. Deletions of nonconserved amino acids in the 14-residue tether, thereby shortening its length, resulted in more drastically reduced IET rate constants. Thus, the deletion of five amino acid residues decreased IET by 70-fold, so that it was rate-limiting in the overall reaction. The steady-state kinetic parameters were also significantly affected by these mutations, with the P111A mutation causing a 5-fold increase in the sulfite K(m) value, perhaps reflecting a decrease in the ability to bind sulfite. The electron paramagnetic resonance spectra of these proline to alanine and deletion mutants are identical to those of wild-type HSO, indicating no significant change in the Mo active site geometry.
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