Developing an Efficient Method for the Incorporation of a Series of Fluorotyrosines in Peptides via Solid Phase Peptide Synthesis

Abstract

The incorporation of unnatural amino acids in peptides and proteins has furthered the investigation of various protein structures and enzyme function. Enzyme residues suggested to be important for catalysis are readily mutated and measured for energetic effects. However, the limited repertoire of naturally occurring amino acids constrains the available substitutions. To obtain a deeper understanding of how enzymes work, unnatural amino acids are used to systematically perturb enzymatic residues. Previous studies in the enzyme ketosteroid isomerase (KSI) used a series of fluorotyrosine analogs to perturb the tyrosine hydrogen bond donor. However, challenges in the synthesis of fluorotyrosine analogs limited their use. To overcome these challenges and extend the series of fluorotyrosines used in enzymatic studies, we are developing an approach to selectively incorporate fluorotyrosines in peptides using silyl‐based and fluorenylmethyloxycarbonyl (Fmoc) based chemistry. Introduction of Fmoc had moderate yields of up to 70%, while silylation of Fmoc‐tyrosine led to low yields of ~20%. Low yields may be attributed to presence of additional undesired silylation products. To overcome this limitation, a series of silylation conditions and additional protecting groups on the amino acid are being evaluated. After optimizing reaction conditions, the dually protected fluorotyrosines will then be used to generate synthetic peptides via solid phase peptide synthesis.Support or Funding InformationThis research was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Numbers; 5UL1GM118979‐03; 5TL4GM118980‐03; 5RL5GM118978‐03. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.