Pseudoenzymatic dealkylation of alkyltins by biological dithiols.
We investigated the time dependence of the degradation of three alkyltin derivatives by a nine amino acid linear peptide (I(1)LGCWCYLR(9)) containing a CXC motif derived from the primary sequence of stannin, a membrane protein involved in alkyltin toxicity. We monitored the reaction kinetics using the intrinsic fluorescence of the tryptophan residue in position 5 of the peptide and found that all of the alkyltins analyzed are progressively degraded to dialkyl derivatives, following a pseudoenzymatic reaction mechanism. The end point of the reactions is the formation of a covalent complex between the disubstituted alkyltin and the peptide cysteines. These data agree with the speciation profiles proposed for polysubstituted alkyltins in the environment and reveal a possible biotic degradation pathway for these toxic compounds.
Porcelli
Fernando
F
Department of Environmental Science, University of Tuscia, 01100 Viterbo, Italy.
Triggiani
Doriana
D
Buck-Koehntop
Bethany A
BA
Masterson
Larry R
LR
Veglia
Gianluigi
G
D000818:Animals; D003640:Dealkylation; D006801:Humans; D015394:Molecular Structure; D009479:Neuropeptides / Q000737:chemistry / Q000235:genetics; D009947:Organotin Compounds / Q000737:chemistry* / Q000633:toxicity; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D014001:Tin / Q000737:chemistry*; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry
D009479:Neuropeptides; D009947:Organotin Compounds; D010455:Peptides; C075692:stannin; D014050:Toluene; D014001:Tin; C004848:dithiol