Copper-catalyzed azide-alkyne click chemistry-based modification of peptides displayed on the surface of yeast cells

Abstract

Short circulating half-life and poor plasma stability and solubility remain key challenges in the field of therapeutic peptide; to overcome these limitations we decided to take advantage of serum albumin, a protein that has the intrinsic capability to bind and transport a large variety of molecules, including drugs. Albumin is not only the major transporter of drugs, but it is also the main fatty acids carrier to tissues. Inspired by the evidence that long fatty acid are able to bind albumin, we thought to increase the stability and half-life of therapeutic peptides by chemically conjugating long fatty acids chain to them. Towards this goal, we applied yeast display technology encoding non-canonical amino-acids. During the first part of the project, we optimized the conditions for the conjugation of peptides displayed on the surface of yeast cells. To assess the efficacy and bio-viability of the cicloaddition reaction, we used alkyne biotin and a peptide bearing an azide group. During the second part of the work, we applied the identified conditions to conjugate an alkyne fatty acid to a peptide and measured its binding affinity against albumin. Most of the collected data have been obtained using flow cytometer technique, through which is possible to gain insights about the cell morphology and aggregation as well as the efficiency of the chemical reaction and the peptide binding affinity