title: Amino acid sequence of spinach ferredoxin:thioredoxin reductase catalytic subunit and identification of thiol groups constituting a redox-active disulfide and a [4Fe-4S] cluster.
abstract: Ferredoxin:thioredoxin reductase is a [4Fe-4S] protein involved in the light regulation of carbon metabolism in oxygenic photosynthesis. This enzyme catalyses the reduction of thioredoxins with light-generated electrons. Ferredoxin:thioredoxin reductase is composed of two dissimilar subunits, a catalytic subunit, and a variable subunit. The catalytic subunit of spinach ferredoxin:thioredoxin reductase, which contains the redox-active disulfide bridge, was sequenced by conventional protein sequencing techniques and the functional roles of all eight cysteine residues were examined by chemical modifications. The polypeptide chain with a calculated molecular mass of 12,959 Da consists of 113 amino acids and has a calculated isoelectric point of 5.30. Six of the eight cysteine residues are clustered as Cys-Pro-Cys and Cys-His-Cys groups. Cys19 and Cys27 are free cysteines with no catalytic function, Cys54 and Cys84 constitute the redox-active disulfide bridge of the active site, and the remaining four, Cys52, Cys71, Cys73, and Cys82 bind the Fe-S cluster.
authors.affiliation: Research Institute for Biosciences, Science University of Tokyo, Japan.
authors.forename: L P
authors.initials: LP
authors.lastname: Chow
authors.forename: H
authors.initials: H
authors.lastname: Iwadate
authors.forename: K
authors.initials: K
authors.lastname: Yano
authors.forename: M
authors.initials: M
authors.lastname: Kamo
authors.forename: A
authors.initials: A
authors.lastname: Tsugita
authors.forename: L
authors.initials: L
authors.lastname: Gardet-Salvi
authors.forename: A L
authors.initials: AL
authors.lastname: Stritt-Etter
authors.forename: P
authors.initials: P
authors.lastname: Schürmann
mesh_terms: D000595:Amino Acid Sequence; D002384:Catalysis; D004220:Disulfides / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D018724:Spinacia oleracea / Q000201:enzymology*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004220:Disulfides; D007506:Iron-Sulfur Proteins; D013438:Sulfhydryl Compounds; D010088:Oxidoreductases; C021588:ferredoxin-thioredoxin reductase