Biochemistry & Analytical Biochemistry

Controlling the conformation of a modified gramicidin S cyclic peptidomimetic with an azobenzene photo-switch

International Conference on Biochemistry

October 10-12, 2016 Kuala Lumpur, Malaysia

John Horsley, Yuan Qi Yeoh, Jingxian Yu and Andrew Abell

University of Adelaide, Australia

Posters & Accepted Abstracts: Biochem Anal Biochem

Abstract:

Secondary structures in proteins contain motifs which are important in determining protein folding and arrangement. The unique folding pattern creates a well-defined structure of protein which governs the function, as emphasized by the quote structure dictates function. Thus, the ability to control the secondary structure of a protein will enable the regulation of protein activity and function. The main objective of this research is to reversibly control the secondary structure of a cyclic peptide photochemically, using UV and visible light. This is demonstrated by incorporating a cis-trans photoisomerizable azobenzene photo-switch into the naturally occurring antibiotic, gramicidin S, to produce a cyclic peptidomimetic, azobenzene-gramicidin S (Azo-GS). Gramicidin S exists as a cyclic peptide with two antiparallel β-strands, linked by two β-turns. The cis isomer of Azo-GS was found to adopt a β-sheet with a β-turn structure, while the trans isomer exists as a random structure. While gramicidin S is active against both Grampositive and Gram negative bacteria, our experimental results showed that Azo-GS is only active against Gram positive bacteria. Both isomers of Azo-GS were tested against the Gram positive bacteria, Staphylococcus aureus and the Gram negative bacteria, Escherichia coli, respectively. The cis isomer, containing the more well-defined secondary structure, was found to be active in suppressing the growth of S. aureus, while the trans isomer was found to be inactive. The findings of this research form the basis for photo-switches to function as potential molecular switches to control the secondary structures and ultimately, the activity of peptides.

Biography :

John Horsley has completed his PhD from the University of Adelaide and currently undertaking Post-doctoral studies from the University of Adelaide, Australia. He is working with the Abell Group focusing on peptide synthesis and has published number of papers in the reputed scientific journals.

Email: john.horsley@adelaide.edu.au