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 2, which is the first organometallic peptide bioconjugate to show significant toxicity against two different tumor cell lines.