Energy-linked nicotinamide nucleotide transhydrogenase : Properties of proton-translocating mitochondrial transhydrogenase from beef heart purified by fast protein liquid chromatography

• Mitochondrial nicotinamide nucleotide transhydrogenasefrom beef heart was purified by a novel procedureinvolving fast protein liquid chromatography andcharacterized with respect to molecular and catalyticproperties. The method is reproducible, gives highlypure transhydrogenase as judged by silver staining,and can be modified to produce large amounts of puretranshydrogenase protein suitable for e.g. sequencingand other protein chemical studies.Transhydrogenase purified by fast protein liquidchromatography is reconstitutively active and pumpsprotons as indicated by an extensive quenching of 9-aminoacridine fluorescence. Under conditions whichgenerate a proton gradient in the absence of a membranepotential the activity of reconstituted transhydrogenaseis close to zero indicating a complete andproper incorporation in the membrane and a preferentialregulation of the enzyme by a proton gradientrather than a membrane potential.Treatment of reconstituted transhydrogenase withN,N-dicyclohexylcarbodiimide results in an inhibitionof proton pump activity without an effect on uncoupledcatalytic activity, suggestingt hat proton translocationand catalytic activities are not obligatory linked orthat this agent separates proton pumping from thecatalytic activity. 

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

Biochemistry

Biokemi

Biochemistry

Biokemi

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