title: Chiral discrimination of D- and L-amino acids using iodinated tyrosines as chiral references: effect of iodine substituent.
abstract: L-Tyrosine and iodinated L-tyrosines, i.e., 3-iodo-L-tyrosine and 3,5-diiodo-L-tyrosine, are successfully used as chiral references for the chiral discrimination of aliphatic, acidic, and aromatic amino acids. Chiral discrimination is achieved by investigating the collision-induced dissociation spectra of the trimeric complex [Cu(II)(ref)(2)(A) - H](+) ion generated by electro spraying the mixture of D- or L-analyte amino acid (A), chiral reference ligand (ref) and M(II)Cl(2) (M = Ni and Cu). The relative abundances of fragment ions resulted by the competitive loss of reference and analyte amino acids are considered for measuring the degree of chiral discrimination by applying the kinetic method. The chiral discrimination ability increases as the number of iodine atom increases on the aromatic ring of the reference and the discrimination is better with Cu when compared with Ni. A large chiral discrimination is obtained for aliphatic and aromatic amino acids using iodinated L-tyrosine as the reference. Computational studies on the different stabilities of the diastereomeric complexes also support the observed differences measured by the kinetic method. The suitability of the method in the measurement of enantiomeric excess over the range of 2% to 100% ee with relative error 0.28% to 1.6% is also demonstrated.
authors.affiliation: National Center for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Kumari
authors.forename: Sripadi
authors.initials: S
authors.lastname: Prabhakar
authors.forename: Mariappanadar
authors.initials: M
authors.lastname: Vairamani
authors.forename: Chebrolu Lavanya
authors.initials: CL
authors.lastname: Devi
authors.forename: Gunturu Krishna
authors.initials: GK
authors.lastname: Chaitanya
authors.forename: Kotamarthi
authors.initials: K
authors.lastname: Bhanuprakash
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D007455:Iodine / Q000737:chemistry*; D008968:Molecular Conformation; D007470:Monoiodotyrosine / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D014443:Tyrosine; D003300:Copper; D007455:Iodine; D007470:Monoiodotyrosine