[CAS NO. 2799-07-7]  H-Cys(Trt)-OH

In cell-based assays, H-Cys(Trt)-OH (S-trityl-l-cysteine) does not prevent cell cycle progression at the S or G2 phases but inhibits both separation of the duplicated centrosomes and bipolar spindle formation, thereby blocking cells specifically in the M phase of the cell cycle with monoastral spindles. Following removal of S-trityl-l-cysteine, mitotically arrested cells exit mitosis normally. In vitro, S-trityl-l-cysteine targets the catalytic domain of Eg5 and inhibits Eg5 basal and microtubule-activated ATPase activity as well as mant-ADP release. It is a tight binding inhibitor and inhibits Eg5-driven microtubule sliding velocity in a reversible fashion with an IC50 of 500 nM.