Effect of divers anions on the electron-transfer reaction between iron and rusticyanin from Thiobacillus ferrooxidans

Journal Article · Tue Oct 01 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00103a008· OSTI ID:5603758

Blake, II, R C; White, K J; Shute, E A ^[1]

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1. Meharry Medical Coll., Nashville, TN (United States)

Rusticyanin is a soluble blue copper protein found in abundance in the periplasmic space of Thiobacillus ferrooxidans, an acidophilic bacterium capable of growing chemolithotrophically on soluble ferrous sulfate. The one-electron-transfer reactions between soluble iron and purified rusticyanin were studied by stopped-flow spectrophotometry in acidic solutions containing each of 14 different anions. The second-order rate constants for both the Fe(II)-dependent reduction and the Fe(III)-dependent oxidation of the rusticyanin varied as a function of the identity of the principal anion in solution. Analogous electron-transfer reactions between soluble iron and bis(dipicolinato)cobaltate(III) or bis(dipicolinato)ferrate(II) were studied by stopped-flow spectrophotometry under solution conditions identical with those of the rusticyanin experiments. Similar anion-dependent reactivity patterns were obtained with soluble iron whether the other reaction partner was rusticyanin or with of the two organometallic complexes. The Marcus theory of outer-sphere electron transfer reactions was applied to this set of kinetic data to demonstrate that the rusticyanin may possess at least two electron-transfer pathways for liganded iron, one where the pattern of electron-transfer reactivity is controlled largely by protein-independent activation parameters and one where the protein exhibits and anion-dependent kinetic specificity. The exact role of rusticyanin in the iron-dependent respiratory electron transport chain of T. ferrooxidans remains unclear.

• DOE Contract Number: FG05-85ER13339
• OSTI ID: 5603758
• Journal Information: Biochemistry; (United States), Vol. 30:39; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
METALLOPROTEINS
BIOCHEMICAL REACTION KINETICS
THIOBACILLUS FERROXIDANS
ELECTRON TRANSFER
ANIONS
COPPER SULFATES
DOSE-RESPONSE RELATIONSHIPS
IRON COMPOUNDS
METABOLISM
BACILLUS
BACTERIA
CHARGED PARTICLES
COPPER COMPOUNDS
IONS
KINETICS
MICROORGANISMS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PROTEINS
REACTION KINETICS
SULFATES
SULFUR COMPOUNDS
SULFUR-OXIDIZING BACTERIA
TRANSITION ELEMENT COMPOUNDS
550200* - Biochemistry