The enzymatic activity of the TrxR is highly dependent on the binding of the cofactor NADPH as it provides reducing equivalents for the reduction of FAD within the catalytic cascade, as described above. Two fragments were observed to bind in the NADPH-binding site (Figure C). One of these fragments has formed an H-bond with His177. Other important amino acids include Arg119, His120, Leu121, Arg178, Arg179, Arg183, and Ile206. In a previous fragment screening on the same protein, H-bonds could be identified to several of the amino acids mentioned above, while others play a role in forming the binding pocket. Since NADPH is a widespread cofactor for many enzymes, an inhibitor for this mycobacterial NADPH-binding pocket would have to be very selective. Therefore, a more detailed evaluation of the hits and their binding is necessary and will be performed after a full evaluation of the fragment screening.