Related Experiment Video
Updated: Jul 6, 2026
EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1
Published on: November 26, 2014
Expression, purification and characterization of the sulfite reductase hemo-subunit, SiR-HP, from Acidithiobacillus
Jia Zeng1, Ming Wang, Xiaojian Zhang
1Department of Bioengineering, School of Resources Processing and Bioengineering, Central South University, Changsha, 410083, People's Republic of China. csuzengjia@yahoo.com.cn
Abstract:
Sulfite reductase (SiR) is a large and soluble enzyme which catalyzes the transfer of six electrons from NADPH to sulfite to produce sulfide. The sulfite reductase flavoprotein (SiR-FP) contains both FAD and FMN, and the sulfite reductase hemoprotein (SiR-HP) contains an iron-sulfur cluster coupled to a siroheme. The enzyme is arranged so that the redox cofactors in the FAD-FMN-Fe(4)S(4)-Heme sequence make an electron pathway between NADPH and sulfite. Here we report the cloning, expression, and characterization of the SiR-HP of the sulfite reductase from Acidithiobacillus ferrooxidans. The purified SiR-HP contained a [Fe(4)S(4)] cluster. Site-directed mutagenesis results revealed that Cys427, Cys433, Cys472 and Cys476 were in ligating with the [Fe(4)S(4)] cluster of the protein.
