title: Antimony(III)-D, L-tartrates exhibit proton-assisted enantioselective binding in solution and in the gas phase.
abstract: The negative ion mode ESI mass spectral analysis of antimony(III)-D- and -L-tartrate ("tartar emetic"), in association with leucine enantiomeric isotopomers, revealed remarkable proton-assisted enantioselective molecular recognition phenomena. The current study infers that recognition of amino acids by antimony(III)-D,L-tartrate complexes requires that the chiral selector associate a proton to become enantioselective. The dianionic selector itself failed to show enantiomeric discrimination capacity. This observation was shown to be consistent both in solution-phase targeting full scan and gas-phase targeting collision threshold dissociation (CTD) experiments. Importantly, this disparity in enantioselective binding capacity between the dianionic and the protonated monoanionic representatives of antimony(III)-D- and -L-tartrates could only be clearly revealed by ESI-MS and tandem mass spectrometry experiments as described herein. This finding urges a more in-depth study of mechanisms associated with exhibited enantiomeric resolving capacity of antimony tartrates in HPLC and CE applications, as well as in former ESI-MS association studies.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX, USA.
authors.forename: Aruna B
authors.initials: AB
authors.lastname: Wijeratne
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Spencer
authors.forename: Jose
authors.initials: J
authors.lastname: Gracia
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Armstrong
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Schug
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000965:Antimony / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D007700:Kinetics; D007930:Leucine / Q000737:chemistry; D015394:Molecular Structure; D019999:Pharmaceutical Solutions / Q000737:chemistry*; D044367:Phase Transition; D011485:Protein Binding; D011522:Protons; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods; D013644:Tartrates / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D005740:Gases; D019999:Pharmaceutical Solutions; D011522:Protons; D012996:Solutions; D013644:Tartrates; D000965:Antimony; D007930:Leucine
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