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The bacterial nitric oxide (NO)-sensing transcriptional regulator NsrR binds a [4Fe-4S] cluster that enables DNA-binding and thus repression of the cell's NO stress response. Upon exposure to NO, the cluster undergoes a complex nitrosylation reaction resulting in a mixture of iron-nitrosyl species, which spectroscopic studies have indicated are similar to well characterized low molecular weight dinitrosyl iron complex (DNIC), Roussin's Red Ester (RRE) and Roussin's Black Salt (RBS). Here we report mass spectrometric studies that enable the unambiguous identification of NsrR-bound RRE-type species, including a persulfide bound form that results from the oxidation of cluster sulfide. In the presence of the low molecular weight thiols glutathione and mycothiol, glutathionylated and mycothiolated forms of NsrR were readily formed.

Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30,000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (α-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol.

The synthesis of a library of nucleoside triphosphate mimetics is described where the Mg(2+) chelated triphosphate sidechain is replaced by an uncharged methylene-triazole linked monosaccharide sidechain. The compounds have been evaluated as inhibitors of Bacillus anthracis pantothenate kinase and a competitive inhibitor has been identified with a K(i) that is 3-fold lower than the K(m) value of ATP.

Actinomycetes produce mycothiol as their major low molecular weight thiol, which parallels the functions of glutathione found in prokaryotes and most Gram-negative bacteria. This review covers progress that has so far been made in terms of its distribution, biosynthesis and metabolic functions, as well as chemical syntheses of mycothiol and alternative substrates and inhibitors of mycothiol biosynthesis and mycothiol-dependent enzymes. 152 references are cited.

A solid phase synthesis of des-myo-inositol mycothiol disulfide and its alpha-configured methyl- and benzyl-glycoside derivatives has been developed. Kinetic characterisation of these compounds has demonstrated their viability as alternative substrates for use in mycothiol disulfide reductase enzyme assays.

This review covers advances/developments in the use of enzymes in synthetic mono-/oligo-saccharide chemistry published in the literature between January 2001 and June 2003. Particular attention is paid to the use of aldolases, ketolases, glycosidases, glycosynthases, lipases, esterases and coupled multi-enzyme biotransformations and 132 references are cited.