... in the presence of inhibitor, v0 is the initial velocity in the absence of inhibitor but with (2%) dimethylsulfoxide The IC50 value was determined by tting the percent inhibition versus inhibitor ... substrate binding [17], highlighting their signicance In SpsB, it is also likely that one or more of the amino acids immediately preceding the catalytic serine form a part of the substrate-binding pocket ... essentiality, the easier accessibility of the catalytic domain for potential inhibitors as a result of being located on the outer side of the cytoplasmic membrane, and the different catalytic mechanism...