Lignin is a macromolecule that
most people don't like. It gets in the way of animals when they are trying to
digest plant polysaccharides, and it gets in our way when we are trying to make
wood cells into paper. Its structure is unpleasantly complex and varies in an
awkward statistical manner from one location to another. Because lignin is
polymerised not by enzymes but by a statistically controlled chemical process
(after enzymic generation of the monomer free
radicals), it cannot be dismantled enzymatically in
the organised way that we expect of other biopolymers, that is by reversal of
the synthetic route. It follows that a lignin molecule cannot be made soluble
without destroying at least some of its characteristic structural features.
Since most classical methods of structure determination work in solution,
that's a problem.
With a grant from the BBSRC IBTI
Club we are looking at the structure of wood, grass and straw lignin, at ways
of solubilising it as pre- or post-treatments for biofuel
production and ways of converting the soluble lignin fragments to saleable
products.