Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Glutamine Complexes with Zn(2+) and Cd(2.).
Complexes of glutamine (Gln) cationized with Zn(2+) and Cd(2+) were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free-electron laser. Electrospray ionization yielded complexes of deprotonated Gln with Zn(2+), [Zn(Gln-H)](+), and intact Gln with CdCl(+), CdCl(+)(Gln). For each complex, the spectra obtained were compared with those for low-energy conformers found using quantum chemical calculations to identify the structures present experimentally. Calculations were performed at the B3LYP/6-311+G(d,p) level for [Zn(Gln-H)](+) and at the B3LYP/def2-TZVP level with an SDD effective core potential on cadmium for CdCl(+)(Gln). The main binding motif observed for the Cd(2+) complex was a charge-solvated, tridentate [N,CO,COsc] structure in which the metal binds to the backbone amino group and the carbonyl oxygens of the carboxylic acid and side-chain amide groups. The Zn(2+) system similarly preferred a [N,CO(-),COsc] binding motif, where binding was observed at the carboxylate site along with the backbone amino and side-chain carbonyl groups. In both cases, the theoretically determined lowest-energy conformers explain the experimental [Zn(Gln-H)](+) and CdCl(+)(Gln) spectra well.
Department of Chemistry, University of Utah , 315 South 1400 East Room 2020, Salt Lake City, Utah 84112, United States.
Georgia C
GC
Boles
Department of Chemistry, University of Utah , 315 South 1400 East Room 2020, Salt Lake City, Utah 84112, United States.
Rebecca A
RA
Coates
Institute for Molecules and Materials, FELIX Laboratory, Radboud University , Toernooiveld 7c, NL-6525 ED Nijmegen, The Netherlands.
Giel
G
Berden
Institute for Molecules and Materials, FELIX Laboratory, Radboud University , Toernooiveld 7c, NL-6525 ED Nijmegen, The Netherlands.|Van't Hoff Institute for Molecular Sciences, University of Amsterdam , Amsterdam, The Netherlands.
Jos
J
Oomens
Department of Chemistry, University of Utah , 315 South 1400 East Room 2020, Salt Lake City, Utah 84112, United States.
P B
PB
Armentrout
D002104:Cadmium / Q000737:chemistry*; D002413:Cations, Divalent / Q000737:chemistry; D003198:Computer Simulation; D005973:Glutamine / Q000737:chemistry*; D007834:Lasers; D008956:Models, Chemical; D055668:Photochemical Processes; D011789:Quantum Theory; D013057:Spectrum Analysis; D015032:Zinc / Q000737:chemistry*
D002413:Cations, Divalent; D002104:Cadmium; D005973:Glutamine; D015032:Zinc