UV and IR double resonance spectroscopy of peptides, DNA bases and clusters.

摘要

These studies focus on the interplay between conformation and dynamics in peptides and nucleobase clusters. A combination of laser desorption mass spectrometry and high resolution ultraviolet and infrared laser spectroscopy makes it possible to observe unique molecular conformations and investigate the dependence of dynamic properties on conformation. The following studies demonstrate that excitation of peptide cations produces fragmentation only for specific ground state conformations. Experimental observations also show that the excited state lifetime of the DNA and RNA base guanine changes several orders of magnitude when it clusters in a specific geometry.;The examination of large biomolecular systems such as proteins by infrared spectroscopy is limited largely by the task of calculating frequencies and energies for the lowest energy structures. These studies examine the possibility to analyze large gas phase peptide data through observing shifts in their near-IR bands and comparing the shifts to the spectra of known peptide structures. Studies are also presented on microhydrates, or clusters with water molecules, and offer a possibility to study the effects on intrinsic properties imposed by the biological environment.