Date of Award
Bachelor of Science
The study of small helical peptides is an area of great interest in biochemistry. Baldwin has shown that salt bridging between residues with oppositely charged side chains can act to stabilize short helices. The order of increased helix stabilization shown by Baldwin was i+4AB>i+4BA>i+3AB>i+3BA where A is a positively charges amino acid side chain and B is a negatively charged amino acid side chain. Most previous studies have dealt with a single type of salt bridge stabilization, either i,i+3, or i,i+4 in a single peptide. This study will address the question of helix stabilization in a system of combined salt bridging. To this end a peptide was synthesized with i,i+3, i,i+4, i,i+3 spacing of oppositely charged residue side chain. The sequence of this peptide is: Ac-YEAAKAAEAAAKAAEAAK-NH2 (designated EK3.3). NMR study of this peptide is being carried out on a 500 MHz instrument. The proton spectrum is being assigned and the conformation determined through the use of TOCSY and NOESY experiments. A second NMR investigation of the 5-mer Ac-YEAAK-NH2 was carried out on a 200MHz instrument. This peptide is designed to allow study of structural stabilization in very small peptides through ionic interaction. The utility of various experiments including standard 1-D 1H spectrum, and 2D COSY, DQF-COSY, Relayed COSY and NOESY on a 200MHz instrument is evaluated.
Ernst, James A., "NMR Studies of Short Salt Bridged Peptides" (1994). Honors Theses. 2043.