The Organic Synthesis of a Dimeric Lignin Probe Utilizing Förster Resonance Energy Transfer (FRET)

Abstract

Lignin is a natural polymer that makes up a large portion of the world's industrial biowaste. It is linked to cellulose and hemicellulose in plant cell walls and is a waste product of the agricultural, forestry, and pulp/paper industry.Lignin can be broken down by fungal peroxidases, but the process is too slow to be considered a commercially feasible option. Several wood-eating organisms such as termites have been shown to depolymerize lignin using bacteria and enzymes in their digestive tract in a fast and efficient manner in comparison to fungal peroxidases. Since bioinformatic and other investigations have to date failed to identify which enzymes are responsible for the breakdown, further investigations are required to identify these depolymerizing enzymes. We propose to synthesize a dimeric lignin probe containing a fluorophore (Cy 5.5) and quencher molecule (BHQ-2) to detect the exact location of these ligninolytic enzymes within these organisms' digestive tract. The Förster Resonance Energy Transfer (FRET) phenomenon will be observed with the probe molecule starting in its quenched or "off" state when intact, but once cleaved at the ß-O-4 linkage of the probe by lignin degrading enzymes, the probe will enter the "on" state, allowing visualization of fluorescence. In this 13-step synthesis, the creation of this dimeric lignin probe will allow researchers to conduct in vivo and in vitro experiments, which are anticipated to allow the development of lignin as alternative biomass for biofuel and fine chemical production.