TY - JOUR
T1 - The homopentameric chlorite dismutase from Magnetospirillum sp.
AU - Freire, Diana M.
AU - Rivas, Maria G.
AU - Dias, André M.
AU - Lopes, Ana T.
AU - Costa, Cristina
AU - Santos-Silva, Teresa
AU - Van Doorslaer, Sabine
AU - González, Pablo J.
N1 - sem pdf conforme despacho.
FCT -
POCTI/QUI/55435/2004
Pest-C/EQB/LA0006/2011
PY - 2015/7/27
Y1 - 2015/7/27
N2 - Chlorite dismutase (Cld) is a b-type heme containing enzyme that catalyzes the reduction of chlorite into chloride plus dioxygen. This enzyme has gained attention because it can be used in the development of bioremediation processes, biosensors, and controlled dioxygen production. In the present work, Cld was purified from Magnetospirillum sp. cells cultured anaerobically with acetate/perchlorate until stationary phase. Biochemical, spectroscopic and X-ray crystallography methods showed that Cld from Magnetospirillum sp. is a ~ 140 kDa homopentamer comprising ~ 27.8 kDa monomers. Preliminary X-ray crystallography studies confirmed the quaternary structure and the presence of one b-type heme per monomer. The EPR spectroscopic signature of the as-purified Cld samples is affected by the buffer composition used during the purification. Potassium phosphate buffer is the only buffer that affected neither the spectral nor the kinetic properties of Cld. Kinetic studies in solution revealed that Cld from Magnetospirillum sp. decomposes chlorite at high turnover rates with optimal pH 6.0. A temperature below 10 °C is required to avoid enzyme inactivation due to cofactor bleaching during turnover, and to achieve full substrate consumption. Cld kinetic parameters were not affected when kinetic assays were performed in the presence of air or under argon atmosphere, but chloride is a weak mixed inhibitor that modifies the EPR signal of as-prepared samples.
AB - Chlorite dismutase (Cld) is a b-type heme containing enzyme that catalyzes the reduction of chlorite into chloride plus dioxygen. This enzyme has gained attention because it can be used in the development of bioremediation processes, biosensors, and controlled dioxygen production. In the present work, Cld was purified from Magnetospirillum sp. cells cultured anaerobically with acetate/perchlorate until stationary phase. Biochemical, spectroscopic and X-ray crystallography methods showed that Cld from Magnetospirillum sp. is a ~ 140 kDa homopentamer comprising ~ 27.8 kDa monomers. Preliminary X-ray crystallography studies confirmed the quaternary structure and the presence of one b-type heme per monomer. The EPR spectroscopic signature of the as-purified Cld samples is affected by the buffer composition used during the purification. Potassium phosphate buffer is the only buffer that affected neither the spectral nor the kinetic properties of Cld. Kinetic studies in solution revealed that Cld from Magnetospirillum sp. decomposes chlorite at high turnover rates with optimal pH 6.0. A temperature below 10 °C is required to avoid enzyme inactivation due to cofactor bleaching during turnover, and to achieve full substrate consumption. Cld kinetic parameters were not affected when kinetic assays were performed in the presence of air or under argon atmosphere, but chloride is a weak mixed inhibitor that modifies the EPR signal of as-prepared samples.
KW - Chlorite dismutase
KW - Enzyme kinetics
KW - EPR spectroscopy
KW - Magnetospirillum
KW - Perchlorate-reducing bacteria
KW - X-ray crystallography
UR - http://www.scopus.com/inward/record.url?scp=84937905674&partnerID=8YFLogxK
U2 - 10.1016/j.jinorgbio.2015.07.006
DO - 10.1016/j.jinorgbio.2015.07.006
M3 - Article
C2 - 26218477
AN - SCOPUS:84937905674
SN - 0162-0134
VL - 151
SP - 1
EP - 9
JO - Journal of Inorganic Biochemistry
JF - Journal of Inorganic Biochemistry
ER -