Dealkylation of organotin compounds by biological dithiols: toward the chemistry of organotin toxicity.

In this Communication, we report evidence for the dealkylation of trialkyltin compounds by a short linear peptide extracted from a small membrane protein (stannin) involved in cellular apoptosis and containing a CXC motif. We show that (a) organotin binding induces the formation of a beta-turn in the linear peptide, (b) both cysteines are necessary for the dealkylation reaction, and (c) stable 1:1 complexes are formed between the peptide and diorganotins that can be observed by ESI-MS. Organotin degradation by biological dithiols may be responsible for both the delayed activity of these toxins in humans and the organotin resistance mechanisms in bacteria.