Purification and partial characterization of a chromate reductase from Bacillus.
A soluble NADH-dependent enzyme capable of reducing hexavalent chromium [Cr(VI)] to the trivalent form [Cr(III)] was purified from chromate-resistant Bacillus QC1-2. An enriched single protein band of 24 kDa was observed by SDS-PAGE following HPLC ion-exchange and size-exclusion procedures. In the latter step, the chromate reductase showed a molecular mass of 44 kDa, which suggested that the enzyme consists of two subunits of about 24 kDa. Purified chromate reductase displayed optimal activity at a temperature and pH of 37 degrees C and 7.0, respectively. The enzyme showed a Km of 0.35 mM for chromate and a Vmax of 50 nmol Cr(VI) reduced per minute per mg protein.
Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia.
J
J
Campos-García
G
G
Martínez-Cadena
R
R
Alvarez-González
C
C
Cervantes
D001407:Bacillus / Q000187:drug effects / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification*; D002840:Chromates / Q000494:pharmacology; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004352:Drug Resistance, Microbial; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010088:Oxidoreductases / Q000302:isolation & purification*
D001426:Bacterial Proteins; D002840:Chromates; D010088:Oxidoreductases; C063243:chromate reductase