Tubulysin H is a highly cytotoxic peptide isolated from the myxobacterial species Archangium geophyra and Angiococcus disciformis[1]. Tubulysin displays extremely potent cytotoxic activity in mammalian cells, including multidrug-resistant cell lines, with IC50 values in the lower nanomolar range[2]. Tubulysin H is a cytotoxic activity tubulysin which inhibits tubulin polymerization and leads to cell cycle arrest and apoptosis[3].
[1]. Steinmetz H, et al. Isolation, crystal and solution structure determination, and biosynthesis of tubulysins--powerful inhibitors of tubulin polymerization from myxobacteria. Angew Chem Int Ed Engl. 2004 Sep 20;43(37):4888-92. [2]. Kubicek K, et al. The tubulin-bound structure of the antimitotic drug tubulysin. Angew Chem Int Ed Engl. 2010 Jun 28;49(28):4809-12. [3]. Vlahov IR, et al. Acid mediated formation of an N-acyliminium ion from tubulysins: a new methodology for the synthesis of natural tubulysins and their analogs. Bioorg Med Chem Lett. 2011 Nov 15;21(22):6778-81.