The isolation of a hexaheme cytochrome from Desulfovibrio desulfuricans and its identification as a new type of nitrite reductase

Journal Article · Tue Dec 01 04:00:00 EST 1981 · J. Biol. Chem.; (United States)

OSTI ID:5842988

Liu, M -C; Peck, Jr, H D

Desulfovibrio desulfuricans (ATCC 27774), a strictly anaerobic sulfate-reducing bacteria, is able to perform anaerobic nitrate respiration in which nitrate is first reduced to nitrite by the action of nitrate reductase, and nitrite reductase then catalyzes the six-electron reduction of nitrite to ammonia. The nitrite reductase was found to be a membrane-bound enzyme and has been purified to electrophoretic homogeneity. The purified enzyme has a minimal M/sub r/=66,000 as judged by sodium dodecyl sulfate gel electrophoresis and contains 6 c-type heme groups/molecule. Pure nitrite reductase exhibits a typical c-type cytochrome absorption spectrum with reduced..cap alpha..-band at 552.5 nm. NADH and NADPH do not function as direct electron donors for the nitrite reductase. Desulfovibrio vulgaris hydrogenase,however, is able to transfer electrons from H/sub 2/ to the nitrite reductase using FAD as the electron transfer mediator. The dithionite-reduced nitrite reductase was demonstrated to be auto-oxidizable even in the presence of potassium cyanide. On addition of nitrite, the dithionite-reduced enzyme is re-oxidized immediately. Hydroxylamine, however, can only partially reoxidize the reduced enzyme. Ascorbate reduces the enzyme to a limited extent and the partially reduced enzyme is neither auto-oxidizable by nitrite or hydroxylamine. Purified nitrite reductase has a pH optimum in the range of 8.0-9.5 and optimal activity at 57/sup o/C. Purified nitrite reductase also has hydroxylamine reductase activity, and the K/sub m/ for nitrite was determined to be 1.14 mM.

• Research Organization: University of Georgia, Athens
• DOE Contract Number: AS09-79ER10499
• OSTI ID: 5842988
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 256:24; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMMONIA
BACTERIA
CATALYSIS
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
DESULFOVIBRIO
ENZYMES
HYDRIDES
HYDROGEN COMPOUNDS
HYDROXYLAMINE
MICROORGANISMS
NITRATES
NITRITES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PURIFICATION
REDUCTION