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Although deoxythymidylate cannot be provided directly by ribonucleotide reductase, the gene encoding thymidylate synthase ThyA is absent from the genomes of a large number of nonsymbiotic microbes. We show that ThyX (Thy1) proteins of previously unknown function form a large and distinct class of thymidylate synthases. ThyX has a wide but sporadic(More)
Nitric oxide (NO) is involved in the regulation of respiration by acting as a competitive ligand for molecular oxygen at the binuclear active site of cytochrome c oxidase. The dynamics of NO in and near this site are not well understood. We performed flash photolysis studies of NO from heme a3 in cytochrome c oxidase from Paracoccus denitrificans, using(More)
Little is known about the catalytic mechanism of the recently discovered ThyX family of flavin-dependent thymidylate synthases that are required for thymidylate (deoxythymidine 5'-monophosphate) synthesis in a large number of microbial species. Using a combination of site-directed mutagenesis and biochemical measurements, we have identified several residues(More)
Biological reactions in protein complexes involve structural dynamics spanning many orders of magnitude in time. In standard descriptions of catalysis by enzymes, the transition state between reactant and product is reached by thermal, stochastic motion. In the ultrashort time domain, however, the protein moiety and cofactor motions leading to altered(More)
The EPR spectral parameters of aa(3) oxidase and cyt c(552) from Paracoccus denitrificans were studied in purified oxidase and enriched cyt c(552). The orientation of the g-tensors of hemes a and c(552) were determined on partially ordered membranes, enriched cyt c(552) and a c(552):aa(3) subcomplex. The known correlation of g-tensor to molecular axes in(More)
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