Synthesis and cytotoxicity of a cobaltcarbonyl–alkyne enkephalin bioconjugate

A solid-phase synthesized propargyl derivative of the neuropeptide leucine-enkephalin (Enk) reacts rapidly and quantitatively with Co(2)(CO)(8) to give the Co(2)(CO)(6)-alkyne labeled peptide , which is the first organometallic peptide bioconjugate to show significant toxicity against two different tumor cell lines.