Marcus Tirado


Office: CLB 306
Office Phone: 392-0562



University of Florida
Ph.D. in Analytical Chemistry, January 2010-present
Graduate Research Project with Dr. Nick Polfer




My research has focused upon investigating the presence of oxazolone vs. macrocycle fragment structures. These isomeric structures are validated via infrared multiple-photon dissociation (IRMPD) spectroscopy using the free electron laser FELIX. In addition, synthetically made cyclic peptides are synthesized as reference compounds to confirm the observation of the macrocycle structure. Earlier work by our group has demonstrated that for a series of oligoglycine b fragments (b2-b8) generated by collision-induced dissociation (CID), the larger b fragments exhibited a progressively higher propensity to form a macrocycle by “head-to-tail” cyclization. As macrocycles are intimately involved in sequence permutation processes, this trend is worrisome for mass spectrometry-based sequencing. Our findings indicate that oxazolone b fragment structures are mainly confined to smaller b ions, where as larger b fragments more readily adopt macrocycles. (vide infra)



'Cyclic peptide as reference system for b ion structural analysis in the gas phase', X Chen, M Tirado, JD Steill, J Oomens, NC Polfer; J. Mass Spectrom., 2011, 46, 1011-1015.


'Disfavoring Macrocycle b Fragments by Constraining Torsional Freedom:The Twisted Case of QWFGLM b6', M Tirado, J Rutters, X Chen, A Yeung, J van Maarseveen, JR. Eyler,G Berden, J Oomens,NC Polfer; JASMS Accepted.


Defying Entropy:IRMPD Spectroscopy of bn (n=4-12) Fragment Ions “How Large Can Macrocycles Become?", M Tirado; Josipa, Grzetic; J Oomens; NC Polfer; Manuscript in Preparation.


'Does Charge Sequestration Impede Macrocyclization?', M Tirado, J Rutters, X Chen, A Yeung, J van Maarseveen, JR. Eyler,G Berden, J Oomens,NC Polfer; Manuscript in Preparation.


'Electric Manipulation of Bioparticles and Macromolecules on Microfabricated Electrodes', Y Huang, K L. Ewalt, M Tirado, R Haigis, A Forster, D Ackley, M J. Heller, J P. O'Connell, and M Krihak ; Anal. Chem., 2001, 73 (7), pp 1549-1559