title: Crystallographic evidence of Gly-D,L-Met oxidation to its sulfoxide in the presence of gold(III): solid solution of the racemic mixture of two diastereoisomers.
abstract: Crystallographic analysis of a solid solution of two diastereoisomers, i.e. ({(1S,R)-1-carboxy-3-[(R,S)-methylsulfinyl]propyl}aminocarbonyl)methanaminium tetrachloridoaurate(III) and ({(1S,R)-1-carboxy-3-[(S,R)-methylsulfinyl]propyl}aminocarbonyl)methanaminium tetrachloridoaurate(III), (C(7)H(15)N(2)O(4)S)[AuCl(4)], has shown that in the presence of gold(III), the methionine part of the Gly-D,L-Met dipeptide is oxidized to sulfoxide, and no coordination to the Au(III) cation through the S atom of the sulfoxide is observed. In view of our observation, literature reports that methionine acts as an N,S-bidentate donor ligand forming stable gold(III) complexes require verification. Moreover, it has been demonstrated that crystallization of the oxidation product leads to a substantial 77:23 excess of both S-methionine/R-sulfoxide and R-methionine/S-sulfoxide over S-methionine/S-sulfoxide and R-methionine/R-sulfoxide. The presence of two different diastereoisomers at the same crystallographic site is a source of static disorder at this site.
authors.affiliation: Department of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland. urszular@amu.edu.pl
authors.forename: Urszula
authors.initials: U
authors.lastname: Rychlewska
authors.forename: Beata
authors.initials: B
authors.lastname: Warzajtis
authors.forename: Biljana D
authors.initials: BD
authors.lastname: Glisic
authors.forename: Snezana
authors.initials: S
authors.lastname: Rajkovic
authors.forename: Milos
authors.initials: M
authors.lastname: Djuran
mesh_terms: D018360:Crystallography, X-Ray; D004151:Dipeptides / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D012451:Safrole / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D004151:Dipeptides; C098230:methionylglycine; D006046:Gold; D012451:Safrole; C005746:sulfoxide