Effects of mutating aromatic surface residues of the heme domain of human sulfite oxidase on its heme midpoint potential, intramolecular electron transfer, and steady-state kinetics

2013 ◽  
Vol 42 (9) ◽  
pp. 3043-3049 ◽  
Author(s):  
Amanda C. Davis ◽  
Matthew J. Cornelison ◽  
Kimberly T. Meyers ◽  
Asha Rajapakshe ◽  
Robert E. Berry ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Midpoint Potential ◽  
Steady State Kinetics ◽  
Heme Domain ◽  
Human Sulfite Oxidase

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 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

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

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

scholarly journals Role of Conserved Tyrosine 343 in Intramolecular Electron Transfer in Human Sulfite Oxidase

2002 ◽  
Vol 278 (5) ◽  
pp. 2913-2920 ◽  
Author(s):  
Changjian Feng ◽  
Heather L. Wilson ◽  
John K. Hurley ◽  
James T. Hazzard ◽  
Gordon Tollin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Human Sulfite Oxidase ◽  
Conserved Tyrosine

Probing the role of a conserved salt bridge in the intramolecular electron transfer kinetics of human sulfite oxidase

2013 ◽  
Vol 18 (6) ◽  
pp. 645-653 ◽  
Author(s):  
Kayunta Johnson-Winters ◽  
Amanda C. Davis ◽  
Anna R. Arnold ◽  
Robert E. Berry ◽  
Gordon Tollin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Salt Bridge ◽  
Sulfite Oxidase ◽  
Intramolecular Electron Transfer ◽  
Electron Transfer Kinetics ◽  
Human Sulfite Oxidase ◽  
Kinetics Of

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

Routes of electron transfer in beef heart cytochrome c oxidase: is there a unique pathway used by all reductants?

1992 ◽  
Vol 70 (5) ◽  
pp. 301-308 ◽  
Author(s):  
M. Crinson ◽  
P. Nicholls
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Reduction Rate ◽  
Artificial Substrates ◽  
Intramolecular Electron Transfer ◽  
State Reduction ◽  
Hydrogen Donors ◽  
Slow Turnover

Cytochrome c oxidase oxidizes several hydrogen donors, including TMPD (N,N,N′,N′-tetramethyl-p-phenylenediamine) and DMPT (2-amino-6,7-dimethyl-5,6,7,8-tetrahydropterine), in the absence of the physiological substrate cytochrome c. Maximal enzyme turnovers with TMPD and DMPT alone are rather less than with cytochrome c, but much greater than previously reported if extrapolated to high reductant levels and (or) to 100% reduction of cytochrome a in the steady state. The presence of cytochrome c is, therefore, not necessary for substantial intramolecular electron transfer to occur in the oxidase. A direct bimolecular reduction of cytochrome a by TMPD is sufficient to account for the turnover of the enzyme. CuA may not be an essential component of the TMPD oxidase pathway. DMPT oxidation seems to occur more rapidly than the DMPT – cytochrome a reduction rate and may therefore imply mediation of CuA. Both "resting" and "pulsed" oxidases contain rapid-turnover and slow-turnover species, as determined by aerobic steady-state reduction of cytochrome a by TMPD. Only the "rapid" fraction (≈70% of the total with resting and ≈85% of the total with pulsed) is involved in turnover. We conclude that electron transfer to the a3CuB binuclear centre can occur either from cytochrome a or CuA, depending upon the redox state of the binuclear centre. Under steady-state conditions, cytochrome a and CuA may not always be in rapid equilibrium. Rapid enzyme turnover by either natural or artificial substrates may require reduction of both and two pathways of electron transfer to the a3CuB centre.Key words: cytochrome c oxidase, cytochrome a, respiration, cyanide, stopped flow.

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.

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