Purification and characterization of the respiratory nitrate reductase of Bacillus stearothermophilus

✍ Scribed by John O. Chikwem; Ronald J. Downey

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 546 KB
• Volume: 126
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(82)90110-5

✦ Synopsis

The reduced methylviolegen-nitrate reductase of the obligate thermophile, Bacillus stearothermophilus NCA strain 2 I84 (ATCC 120 16), has been purified to electrophoretic homogeneity, 53-fold with a yield of 12.5%. The purification procedure involved solubilization with octyl glucoside, ammonium sulfate precipitation, ion-exchange, and molecular sieve chromatography. The molecular weight of the enzyme was estimated by polyacrylamide gel electrophoresis to be about 2 10,000. The enzyme possesses two subunits of 150,000 and 44,000 daltons in equimolar ratio, and no cytochrome. There are 6 atoms of nonheme iron and 12 mol of labile sulfide in 1 mol of the purified enzyme. The 44,OOOdalton j3 subunit is the smallest of all the characterized bacterial nitrate reductases and is very close to the size of the 6' subunit of Escherichia coli. The various j3 components of other bacterial nitrate reductases are probably derived from this 44,000-dalton subunit.