Chemical Modification of Silk Proteins via Palladium‐Mediated Suzuki−Miyaura Reactions

Abstract

AbstractSuzuki−Miyaura cross‐coupling reactions are used to modify the tyrosine residues on Bombyx mori silkworm silk proteins using a water‐soluble palladium catalyst. First, model reactions using tyrosine derivatives are screened to determine optimal reaction conditions. For these reactions, a variety of aryl boronic acids, solvents, buffers, and temperature ranges are explored. Qualitative information on the reaction progress is collected via high‐performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR). Optimized reactions are then applied to silk proteins. It is demonstrated the ability to modify silk fibroin in solution by first iodinating the tyrosine residues on the protein, and then carrying out Suzuki‐Miyaura reactions with a variety of boronic acid derivatives. Modification of silk is confirmed with NMR, ion‐exchange chromatography (IEC), UV‐vis, and infrared spectroscopy (IR).