Doing the methylene shuffle--further insights into the inhibition of mitotic kinesin Eg5 with S-trityl L-cysteine

S-Trityl L-cysteine (STLC) is an inhibitor of the mitotic Kinesin Eg5 with potential as an antimitotic chemotherapeutic agent. We previously reported the crystal structure of the ligand-protein complex, and now for the first time, have quantified the interactions using a molecular dynamics based approach. Based on these data, we have explored the SAR of the trityl head group using the methylene shuffle strategy to expand the occupation of one of the hydrophobic pockets. The most potent compounds exhibit strong (<100 nM) inhibition of Eg5 in the basal ATPase assay and inhibit growth in a variety of tumour-derived cell lines.