Structure determination and synthesis of lysine isopeptides influencing on cell proliferation.

The clavicepamines are lysine-rich basic proteins isolated from saprophytic culture of ergot (Claviceps purpurea), having human pharmacological importance. Based on structure determinations, it was demonstrated that the epsilon-lysine (poly)peptides are the fundamental structural units of clavicepamines. To study the relationship between chemical structure and biological effect, solution and solid-phase synthesis of lysine isopeptides were performed. Poly-epsilon-lysines were synthesized with polycondensation via application of p-nitrophenylester temporarily protecting groups together with simultaneous activation. The biological investigations of poly-epsilon-lysines showed a cell-proliferation retarding effect, so they inhibit growth of some animal tumors, practically without toxic side effects.