Current chemotherapies against trypanosomiasis are beset with diverse challenges, a situation which underscores the numerous research efforts aimed at finding newer and effective treatments. Arginine kinase of trypanosome has been validated as target for drug development against trypanosomiasis. The present study investigated the interaction between a recombinant form of the arginine kinase (rTbAK) of trypanosome and gallotannin. The interaction between gallotannin and recombinant arginine kinase of Trypanosoma brucei caused significant decrease of enzyme activity. Kinetic analysis revealed the interaction to be of noncompetitive inhibition. Further thermodynamic analysis showed that the interaction between gallotannin and the recombinant arginine kinase was nonspontaneous and involved hydrophobic forces. The values and the FRET analysis suggest that static quenching of fluorescence intensity by gallotannin was static. Data revealed inhibitory interactions between gallotannin and rTbAK of trypanosome. Although the mechanism of inhibition is not clear yet, molecular docking studies are ongoing to clearly define the inhibitory interactions between the gallotannin and rTbAK. The knowledge of such binding properties would enrich development of selective inhibitors for the arginine kinase of Trypanosoma brucei. 1. Introduction African trypanosomiasis is one of the neglected diseases currently ravaging several countries in the sub-Saharan Africa. The disease, which affects both humans and animals, is fatal if left untreated. Chemotherapy which forms the major means of controlling the disease scourge is currently faced with many challenges including limited efficacy, unwanted toxicity, and emergence of resistant strain of trypanosomes [1]. These and other factors underscore the research efforts aimed at finding better chemotherapy for trypanosomiasis. Arginine kinase (AK) is a phosphotransferase enzyme, which has been validated as a drug target for selective trypanocide development [2–5]. The enzyme mediates the reversible formation of a phosphagen from L-arginine and ATP [2]. Phosphoarginine plays key role in providing the needed energy for cellular activity until metabolic events such as glycolysis and oxidative phosphorylation are switched on [6–8]. In a separate study, it has been demonstrated that AK is highly critical to the survival of the trypanosomes under stressful condition, particularly for the bloodstream forms of trypanosome, which are constantly being exposed to prooxidants in the mammalian host blood environment [9]. The AK could serve as ready
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