Unveiling the structure and ultrastructure of lignin carbohydrate complexes in softwoods

• Lignocellulose-based polymers are presently being investigated for potential as raw materials for polymer industry. However, covalent bonds between carbohydrates and lignin, so called lignin carbohydrate complexes (LCCs) present one of the factors impeding clean fractionation of the polymers. Understanding the chemical structure of LCCs in relation to the cell wall ultra-structure therefore provides relevant insight for technical fractionation. In the present work, new mild analytical protocols for LCCs were developed and fractions thereof subjected to detailed structural/ultra-structural characterization. When combined with size exclusion chromatography, the application of mono-component ploysaccharidases proved to be crucial for the identification of LCC moieties and provided indirect evidence for existence of lignin-carbohydrate bonds. The carbohydrate composition of the LCC moieties was essential to determination of the ultra-structural origin of the LCC types. Analytical 31P NMR of the LCCs and of their thioacidolysis products was useful in unveiling lignin structure in LCCs. A complete structure/ultra-structure relationship of LCCs in softwood was determined.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

Cell wall LCCs

Lignin carbohydrate complexes (LCCs)

Middle lamella LCCs

Mono-component enzymes

PH neutral fractionation

beta mannosidase

galacturonic acid

glucan synthase

lignocellulose

polygalacturonase

xylan endo 1

3 beta xylosidase

alkalinity

article

bromination

carbohydrate analysis

carbohydrate metabolism

centrifugation

dissolution

fractionation

gel permeation chromatography

hydrolysis

pH

quantitative analysis

structure analysis

ultrastructure

wood

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