Date of Award
Bachelor of Science
One of the most common structural elements in proteins is the a-helix. The main goal of this study was to see If the helical properties of short peptide chains could be increased by the formation of salt bridges between side chains. It has been shown that i,i+4 peptides posses helic; I characier. The research that has been done was to make a hybrid peptide chain, that had partial i,i+4 and partial i,i+3 salt bridge formation. The hybrid peptide was a i+4, i+3, i+4 peptide chain. The overall purpose of making this type of hybrid peptide was to make the approximate number of residues in a tum of the helix closer to the 3.6 residues, which is the number of residues in a natural tum of the helix. The charged amino acids used were positive lysine residues and negative glutamate residues. The peptides were constructed through solid-phase synthesis and purified using HPLC. The stability of the peptides were examined theoretically using molecular modeling and experimentally the helicity was tested by Circular Dichroism. The experimental results of the mixed spaced peptides were compared to Stellwagon's and Baldwin's uniformly spaced peptides. This study found that the mixed spaced peptides were at least as stable as the uniformly spaced peptides. A version of the uniformly spaced peptide was also synthesized, but assumed a b-sheet configuration, which is currently under investigation through both experimental and theoretical studies.
Nicoletta, Angelo Carmine, "Influence of Salt Bridge Formation on Helix Stability" (1995). Honors Theses. 2046.