Intramolecular electron transfer controls nitrite reduction in molybdenum-containing sulfite oxidase

Nitric Oxide ◽  
2014 ◽  
Vol 42 ◽  
pp. 113
Author(s):  
Guenter Schwarz ◽  
Sabina Krizowski ◽  
Jun Wang ◽  
Dimitri Niks ◽  
Courtney Sparacino-Watkins ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Nitrite Reduction ◽  
Intramolecular Electron Transfer

Mechanism of nitrite-dependent NO synthesis by human sulfite oxidase

2019 ◽  
Vol 476 (12) ◽  
pp. 1805-1815 ◽  
Author(s):  
Daniel Bender ◽  
Alexander Tobias Kaczmarek ◽  
Dimitri Niks ◽  
Russ Hille ◽  
Guenter Schwarz
Keyword(s):  
Electron Transfer ◽  
Spectroscopic Studies ◽  
Sulfite Oxidase ◽  
Nitrite Reduction ◽  
Intramolecular Electron Transfer ◽  
Intermembrane Space ◽  
Electron Transfer Mechanism ◽  
Physiological Relevance ◽  
Order Of Magnitude ◽  
Human Sulfite Oxidase

AbstractIn addition to nitric oxide (NO) synthases, molybdenum-dependent enzymes have been reported to reduce nitrite to produce NO. Here, we report the stoichiometric reduction in nitrite to NO by human sulfite oxidase (SO), a mitochondrial intermembrane space enzyme primarily involved in cysteine catabolism. Kinetic and spectroscopic studies provide evidence for direct nitrite coordination at the molybdenum center followed by an inner shell electron transfer mechanism. In the presence of the physiological electron acceptor cytochrome c, we were able to close the catalytic cycle of sulfite-dependent nitrite reduction thus leading to steady-state NO synthesis, a finding that strongly supports a physiological relevance of SO-dependent NO formation. By engineering SO variants with reduced intramolecular electron transfer rate, we were able to increase NO generation efficacy by one order of magnitude, providing a mechanistic tool to tune NO synthesis by SO.

The catalytic mechanism for NO production by the mitochondrial enzyme, sulfite oxidase

2019 ◽  
Vol 476 (13) ◽  
pp. 1955-1956
Author(s):  
Bulent Mutus
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Protein Engineering ◽  
Catalytic Mechanism ◽  
Spectroscopic Studies ◽  
Sulfite Oxidase ◽  
Nitrite Reduction ◽  
No Production ◽  
Intramolecular Electron Transfer ◽  
Vis Spectroscopy

Abstract Recently, Guenter Schwarz and colleagues published an elegant study in the Biochemical Journal (2019) 476, 1805–1815 which combines kinetic and spectroscopic studies with protein engineering to provide a mechanism for sulfite oxidase (SO)-catalyzed nitrite reduction that yields nitric oxide (NO). This work is noteworthy as it demonstrates that (i) for NO generation, both sulfite and nitrite must bind to the same molybdenum (Mo) center; (ii) upon sulfite reduction, Mo is reduced from +6 (MoVI) to +4 (MoIV) and MoIV reduces nitrite to NO yielding MoV; (iii) the heme moiety, linked to the Mo-center by an 11 amino acid residue tether, gets reduced by intramolecular electron transfer (IET) resulting in MoV being oxidized to MoVI; (iv) the reduced heme transfers its electron to a second nitrite molecule converting it to NO; (v) the authors demonstrate steady-state NO production in the presence of the natural electron acceptor cytochrome c; (vi) Finally, the authors use protein engineering to shorten the heme tether to reduce the heme-Mo-center distance with the aim of increasing NO production. Consequently, the rate of IET to cytochrome c is decreased but the enzymatic turnover rate for NO production is increased by ∼10-fold. This paper is unique as it provides strong evidence for a novel mechanism for steady-state NO production for human mitochondrial SO and serves as a potential template for studying NO production mechanisms in other enzymes by integrating the information gained from enzyme kinetics with EPR and UV/vis spectroscopy and protein engineering.

The Pathogenic Human Sulfite Oxidase Mutants G473D and A208D Are Defective in Intramolecular Electron Transfer†

Biochemistry ◽  
2005 ◽  
Vol 44 (42) ◽  
pp. 13734-13743 ◽  
Author(s):  
Changjian Feng ◽  
Heather L. Wilson ◽  
Gordon Tollin ◽  
Andrei V. Astashkin ◽  
James T. Hazzard ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Human Sulfite Oxidase

The pH dependence of intramolecular electron transfer rates in sulfite oxidase at high and low anion concentrations

1999 ◽  
Vol 4 (4) ◽  
pp. 390-401 ◽  
Author(s):  
Andrew Pacheco ◽  
James T. Hazzard ◽  
G. Tollin ◽  
J. H. Enemark
Keyword(s):  
Electron Transfer ◽  
Ph Dependence ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Transfer Rates

Chicken liver sulfite oxidase. Kinetics of reduction by laser-photoreduced flavins and intramolecular electron transfer

Biochemistry ◽  
1988 ◽  
Vol 27 (8) ◽  
pp. 2918-2926 ◽  
Author(s):  
Cary A. Kipke ◽  
Michael A. Cusanovich ◽  
Gordon Tollin ◽  
Roger A. Sunde ◽  
John H. Enemark
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Chicken Liver ◽  
Intramolecular Electron Transfer ◽  
Kinetics Of ◽  
Kinetics Of Reduction

scholarly journals Effects of Interdomain Tether Length and Flexibility on the Kinetics of Intramolecular Electron Transfer in Human Sulfite Oxidase

Biochemistry ◽  
2010 ◽  
Vol 49 (6) ◽  
pp. 1290-1296 ◽  
Author(s):  
Kayunta Johnson-Winters ◽  
Anna R. Nordstrom ◽  
Safia Emesh ◽  
Andrei V. Astashkin ◽  
Asha Rajapakshe ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Human Sulfite Oxidase ◽  
Kinetics Of

Effect of Solution Viscosity on Intramolecular Electron Transfer in Sulfite Oxidase†

Biochemistry ◽  
2002 ◽  
Vol 41 (18) ◽  
pp. 5816-5821 ◽  
Author(s):  
Changjian Feng ◽  
Rohit V. Kedia ◽  
James T. Hazzard ◽  
John K. Hurley ◽  
Gordon Tollin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Solution Viscosity ◽  
Intramolecular Electron Transfer

Inhibition of intramolecular electron transfer in sulfite oxidase by anion binding

1992 ◽  
Vol 114 (24) ◽  
pp. 9662-9663 ◽  
Author(s):  
Eric P. Sullivan ◽  
James T. Hazzard ◽  
Gordon Tollin ◽  
John H. Enemark
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Anion Binding ◽  
Intramolecular Electron Transfer

scholarly journals Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography

2016 ◽  
Vol 113 (11) ◽  
pp. 2928-2933 ◽  
Author(s):  
Yohta Fukuda ◽  
Ka Man Tse ◽  
Takanori Nakane ◽  
Toru Nakatsu ◽  
Mamoru Suzuki ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Nitrite Reductase ◽  
Transient State ◽  
Carbonyl Oxygen ◽  
Nitrite Reduction ◽  
Hydroxyl Group ◽  
Intramolecular Electron Transfer ◽  
Metal Centers ◽  
Substrate Complex

Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme–substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-Å resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-Å resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes.

Essential Role of Conserved Arginine 160 in Intramolecular Electron Transfer in Human Sulfite Oxidase†

Biochemistry ◽  
2003 ◽  
Vol 42 (42) ◽  
pp. 12235-12242 ◽  
Author(s):  
Changjian Feng ◽  
Heather L. Wilson ◽  
John K. Hurley ◽  
James T. Hazzard ◽  
Gordon Tollin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Essential Role ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Human Sulfite Oxidase
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