Ferredoxin-thioredoxin reductase: a catalytically active dithiol group links photoreduced ferredoxin to thioredoxin functional in photosynthetic enzyme regulation
The mechanism by which the ferredoxin-thioredoxin system activates the target enzyme, NADP-malate dehydrogenase, was investigated by analyzing the sulfhydryl status of individual protein components with (/sup 14/C)iodoacetate and monobromobimane. The data indicate that ferredoxin-thioredoxin reductase (FTR)--an iron-sulfur enzyme present in oxygenic photosynthetic organisms--is the first member of a thiol chain that links light to enzyme regulation. FTR possesses a catalytically active dithiol group localized on the 13 kDa (similar) subunit, that occurs in all species investigated and accepts reducing equivalents from photoreduced ferredoxin and transfers them stoichiometrically to the disulfide form of thioredoxin m. The reduced thioredoxin m, in turn, reduces NADP-malate dehydrogenase, thereby converting it from an inactive (S-S) to an active (SH) form. The means by which FTR is able to combine electrons (from photoreduced ferredoxin) with protons (from the medium) to reduce its active disulfide group remains to be determined.
- Research Organization:
- Universite de Paris-Sud, Orsay, France
- OSTI ID:
- 6075597
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 256:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FERREDOXIN
BIOLOGICAL FUNCTIONS
OXIDOREDUCTASES
REDOX REACTIONS
CARBON 14 COMPOUNDS
CATALYSIS
ELECTRONS
PHOTOSYNTHESIS
PLANTS
PROTONS
STOICHIOMETRY
TOLUENE
TRACER TECHNIQUES
ALKYLATED AROMATICS
AROMATICS
BARYONS
CHEMICAL REACTIONS
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
FUNCTIONS
HADRONS
HYDROCARBONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEPTONS
METALLOPROTEINS
NUCLEONS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PROTEINS
SYNTHESIS
550201* - Biochemistry- Tracer Techniques