Collisional activation of [14Pro+2H]2+ clusters: chiral dependence of evaporation and fission processes.
Ion mobility/mass spectrometry techniques are used to investigate the dissociation of the small proline cluster [14Pro+2H](2+) produced by electrospray ionization. While this cluster is known to prefer heterochiral compositions (i.e., mixed L- and D-compositions, J. Phys. Chem. A, submitted for publication), it is possible to produce homochiral forms by electrospraying solutions containing only L- or D-proline. Differences in the measured cross sections for [14Pro+2H](2+) produced from enantiomerically pure (100% l or 100% d) or racemic (50:50 l/d) solutions indicate that homochiral and heterochiral clusters have different structures. Upon low-energy collisional activation, both the heterochiral and homochiral doubly charged structures evaporate neutral proline monomers, resulting in the formation of [xPro+2H](2+) ions (where x = 9-13). At higher activation energies, there is evidence that these smaller clusters (primarily [10Pro+2H](2+)) fission to produce [xPro+H](+) (where x = 1-6). Analysis of product ion intensities reveals a strong chiral preference associated with fissioning. Products of evaporation also show a chiral dependence but to a lesser extent.
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
Natalya
N
Atlasevich
Alison E
AE
Holliday
Stephen J
SJ
Valentine
David E
DE
Clemmer
D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011392:Proline / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods
D007477:Ions; D011392:Proline