NMR spectroscopy: An invaluable tool to identify lignin structural modifications induced by oxidative enzymes

This chapter provides a comprehensive guide to the acquisition, processing, and analysis of NMR data for investigating the behaviour of lignins in enzymatic treatment. The necessary pre-treatments to obtain purified lignin samples, free from enzymes and contaminants, are described prior to the spectroscopic analyses. Detailed instructions for using quantitative 13C NMR with an internal standard are then given to determine the abundance of lignin bonding patterns, expressed both as mmol/g of lignin and normalised on the basis of an aromatic unit. Quantitative 31P NMR is the favoured analytical tool used to distinguish and quantify hydroxyl groups, which are key targets for oxidases. Finally, both qualitative and quantitative HSQC analyses (QQ-HSQC and HSQC0) are described to monitor overall changes in lignin bonding patterns.