Investigation of Secondary Structure Elements by IR/UV Double Resonance Spectroscopy:  Analysis of an Isolated β-Sheet Model System

• Published in: Journal of the American Chemical Society Vol. 130; no. 14; pp. 4692 - 4698
• Main Authors: Fricke, Holger, Funk, Andreas, Schrader, Thomas, Gerhards, Markus
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.04.2008
• Subjects: Dipeptides - chemistry; Peptides - chemistry; Protein Structure, Secondary; Quantum Theory; Spectrophotometry, Infrared - methods; Spectrophotometry, Ultraviolet - methods
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/ja076031c

An isolated β-sheet model system is investigated in a molecular beam experiment by means of mass- and isomer-selective IR/R2PI double resonance spectroscopy as well as ab initio and DFT calculations. As the exclusive intermolecular assembly, a β-sheet motif is formed by spontaneous dimerization of two isolated peptide molecules. This secondary structure is produced from the tripeptide model Ac-Val-Tyr(Me)-NHMe without any further environment to form the binding motif which is analyzed by both the characteristic amide A and I vibrations. The experimental and theoretical investigations yield the assignment to an antiparallel β-sheet model. The result of this detailed spectroscopic analysis on an isolated β-sheet model indicates that there are intrinsic properties of a β-sheet structure which can be formed without a solvent or a peptidic environment.