Escherichia coli thioredoxin reductase

Escherichia coli thioredoxin reductase refined at 2 A resolution. Implication of a large conformational change during catalysis. Journal of Molecular Biology, 236, 800-16. 

Svergun et al. [138] studied three proteins lysozyme, Escherichia coli thioredoxin reductase, and E. coli ribonucleotide reductase protein Rl, in aqueous solution, using x-ray and neutron scattering. The density of the water of the first hydiadon shell of these proteins differed from that of bulk water, the average relative deusities were 1.08 0.02, 1.16 0.05, and 1.12 0.06. These experimental values are smaller than those calculated from the packing, 1.22 according to Gerstein and Chothia [137], but still appreciable. 

Mammalian thioredoxin reductase is able to reduce many substances in addition to thioredoxin such as insulin, vitamin K, alloxan, and others, while Escherichia coli enzyme is a... 

Mao, S. S., Yu, G. X., Chalfoun, D., and Stubbe, J., 1992, Characterization of C439SR1, a mutant of Escherichia coli ribonucleotide diphosphate reductase evidence that C439 is a residue essential for nucleotide reduction and C439SR1 is a protein possessing novel thioredoxin-like activity, Biochemistry 31 9752n9759. 

High-level expression in Escherichia coli of selenocysteine-containing rat thioredoxin reductase utilizing gene fusions with engineered bacterial-type SECIS elements and co-expression with 80. 

Regeneration of the ribonucleotide reductase is accomplished in Escherichia coli and in mammals by thioredoxin, a dithiol polypeptide (M.W. 12,000) coenzyme, which also plays a role in other protein disulfide reductase reactions. In thioredoxin, two cysteine residues in the sequence -Cys-Gly-Pro-Cys are converted to cystine. Reduced thioredoxin is regenerated by thioredoxin reductase, a flavoprotein enzyme that uses NADPH + H+. 

Ribonucleotide reductase of Escherichia coli, which catalyzes the reduction of ribonucleoside 5 -diphosphates to 2 -deoxynucleoside 5 -diphos-phates, consists of two nonidentical subunits, proteins B1 and B2. In the presence of Mg , the two subunits form a 1 1 complex of active enzyme. When separated, neither subunit has any known biological activity. Protein B1 has a molecular weight of 160,000, contains the active dithiols, is capable of interacting with thioredoxin, and contains... 

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