Substrate Specificity of Trypanothione Reductase

Ellman's-reagent-mediated regeneration of trypanothione in situ: substrate-economical microplate and time-dependent inhibition assays for trypanothione reductase.

Trypanothione reductase (TryR) is a key enzyme involved in the oxidative stress management of the Trypanosoma and Leishmania parasites, which helps to maintain an intracellular reducing environment by reduction of the small-molecular-mass disulphide trypanothione (T[S](2)) to its di-thiol derivative dihydrotrypanothione (T[SH](2)). TryR inhibition studies are currently impaired by the prohibiti...

Substrate and inhibitor specificity of Mycobacterium avium dihydrofolate reductase.

Dihydrofolate reductase (EC 1.5.1.3) is a key enzyme in the folate biosynthetic pathway. Information regarding key residues in the dihydrofolate-binding site of Mycobacterium avium dihydrofolate reductase is lacking. On the basis of previous information, Asp31 and Leu32 were selected as residues that are potentially important in interactions with dihydrofolate and antifolates (e.g. trimethoprim...

Substrate specificity of human ribonucleotide reductase from Molt-4F cells.

Nucleoside triphosphates were examined as the activator for various nucleoside diphosphate reductions catalyzed by a highly purified ribonucleotide reductase obtained from Molt-4F cultured human cells. It was found that cytidine 5'-diphosphate and uridine diphosphate reductions are activated by adenosine 5'-triphosphate with apparent Ka's of 0.63 +/- 0.03 (S.E.) and 1.25 +/- 0.10 mM, respective...

Hydrogen donor specificity of cobamide-dependent ribonucleotide reductase and allosteric regulation of substrate specificity.

Trypanothione-dependent synthesis of deoxyribonucleotides by Trypanosoma brucei ribonucleotide reductase.

Trypanosoma brucei, the causative agent of African sleeping sickness, synthesizes deoxyribonucleotides via a classical eukaryotic class I ribonucleotide reductase. The unique thiol metabolism of trypanosomatids in which the nearly ubiquitous glutathione reductase is replaced by a trypanothione reductase prompted us to study the nature of thiols providing reducing equivalents for the parasite sy...