Methyl viologen-linked sulfite reductase from spinach leaves

Journal Article · Wed Jan 01 04:00:00 EST 1969 · J. Biol. Chem.; (United States)

OSTI ID:5294184

Asada, K; Tanura, G; Bandurski, R S

A methyl viologen-linked sulfite reductase from spinach leaves was cleaved into two protein fractions. Both fractions were required for the oxidation of reduced methyl viologen with sulfite and the formation of sulfide under the assay conditions used. One fraction could be replaced by bovine serum albumin, by several other crystalline proteins, by thiol and disulfide compounds, or by yeast RNA. The other fraction, sulfite reductase, has been purified 492-fold. The enzyme was homogeneous by ultracentrifugation but not by electrophorsis with polyacrylamide gel or cellulose acetate. The enzyme contained 0.76 g atom of iron per 84,000 g of protein. Negligible amounts of flavin are observed, indicating that flavin is not directly involved in catalysis of sulfite reduction. Sulfite reductase, in the oxidized form, has absorbtion maxima at 279, 404, and 589 millimicrons. The last two maxima were shifted and diminished upon reduction with sodium borohydride and partially restored by sulfite. Absorption at 404 and 589 millimicrons was modified by cysteine, cyanide, and carbon monoxide. Prior incubation of the reduced enzyme with sulfite prevented inhibition by p-chloromercuribenzoate and carbon monoxide. The inhibition of sulfite reductase by carbon monoxide was reversed by light. Thus, the sulfite reductase has some of the properties of a hemoprotein. After cleavage, sulfite reductase was inactivated by reduced methyl viologen unless albumin, cysteine, cystine, sulfite, or RNA were present. The possible role of these compounds in prevention of reductase inactivation by methyl viologen is discussed. After cleavage, the enzyme ceased to catalyze the reduction of sulfite and hydroxylamine. The ratio of these activities remained constant through the later purification steps, and it is concluded that hydroxylamine reduction, but not nitrite reduction, is catalyzed by sulfite reductase.

• OSTI ID: 5294184
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 244:18; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

560303* -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ABSORPTION
ALBUMINS
AMINES
AMINO ACIDS
AZINES
BIPYRIDINES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CENTRIFUGATION
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CYANIDES
CYSTEINE
ECOSYSTEMS
ELEMENTS
ENZYMES
FOOD
HETEROCYCLIC COMPOUNDS
HYDROXYLAMINE
IRON
ISOALLOXAZINES
LEAVES
METALS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PRODUCTION
PROTEINS
PYRIDINES
QUALITATIVE CHEMICAL ANALYSIS
RNA
SEPARATION PROCESSES
SPINACH
SULFIDES
SULFITES
SULFUR COMPOUNDS
TERRESTRIAL ECOSYSTEMS
THIOLS
TRANSITION ELEMENTS
ULTRACENTRIFUGATION
VEGETABLES