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Modification of the Prolyl Ring of Val-Pro-Ala and the Impact of this Modification on b 2 Ion Structure Matthew Bernier, Julia Chamot-Rooke, Ashley Gucinski, & Vicki Wysocki International Symposium on Molecular Spectroscopy 68th Meeting 6/19/13

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Roepstorff P, Fohlman J. Biomed. Mass Spectrom. (1984) 11 (11): 601. b2b2 y2y2 b fragment ion formation Collision induced dissociation (Ar/He)

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oxazolone diketopiperazine cis trans b fragment ion formation

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VS Isomerization (trans-cis) Rel. Energy 20 kcal/mol 13 kcal/mol JACS, 1988. 110(13): p. 4212-4216. 2.5 kcal/mol 0.5 kcal/mol What makes proline so special?

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Gucinski et al. Phys Chem A 2013. Just Accepted Only ONE of the XxxPro peptides here show no evidence of diketopiperazine b 2 structure What makes proline so special?

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Collagen Triple Helix: Substituent stability Biopolymers, Vol. 59, 2428 (2001) PNAS January 12, 2010 vol. 107, 559564 ProHypGly ProProGly 30.5 C 36 C TmTm

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Collagen Triple Helix: Substituent stability PNAS January 12, 2010 vol. 107, 559564 34 C 58 C TmTm

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J. Org. Chem. 2004, 69, 8565-8573. J. Am. Chem. Soc., Vol. 123, No. 4, 2001 Effects of prolyl ring substitution X = H, OH, or F Y = H X = H Y = OH or F

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J. Org. Chem. 2004, 69, 8565-8573. Can we influence oxazolone/diketo prevalance with substituent influence on trans/cis isomerization barrier? Effects of prolyl ring substitution

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Does wavelength excite vibrational mode of molecule? Yes Fragmentation Efficiency No + No fragments = no intensity @ wavenumber scanned + Molecule of interest ionized into the gas phase + MS trapping and irradiation with tunable IR laser Electrospray Ionization (ESI) Fragmentation Efficiency: I fragments / I precursor + + OR Fragment ions detected- measurable intensity at vibrationally active energy CLIO Infrared Laser Tunable 1000-2000 cm -1 Action Infrared Multi-Photon Dissociation Spectroscopy

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K trans/cis = 4.6 ValXxx Vibrational Spectroscopy - ValPro Gucinski, A. C.; Chamot-Rooke, J.; Steinmetz, V.; Somogyi, A.; Wysocki, V. H. J Phys Chem A 2013, 117, 1291.

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ValXxx Vibrational Spectroscopy Val(Y-Flp) K trans/cis = 6.7 J. Org. Chem. 2004, 69, 8565-8573.

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ValXxx Vibrational Spectroscopy Val(X-Flp) K trans/cis = 2.5 J. Org. Chem. 2004, 69, 8565-8573.

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ValXxx Vibrational Spectroscopy K trans/cis = 2.5 K trans/cis = 4.6 K trans/cis = 6.7 Gucinski, A. C.; Chamot-Rooke, J.; Steinmetz, V.; Somogyi, A.; Wysocki, V. H. J Phys Chem A 2013, 117, 1291. X-Flp Y-Flp Pro x10 x25 x50

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Gas phase vs. solution phase structure

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Y-FlpX-Flp Oxazolone Diketopiperazine

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Tandem MS 3 comparison: V(Xflp) vs V(YFlp) Oxazolone Diketopiperazine

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Conclusions Holds true in gas phase

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Acknowledgments NIH GMR01-51387