Enzyme digestion, lignin

Pew, J. C. Weyna, P. Fine Grinding, Enzyme Digestion, and the Lignin-... 

Pew JC, Weyna P (1962) Fine grinding, enzyme digestion, and the lignin cellulose bond in wood Tappi 45 247-256... 

Scheijen, M.A. and J.J. Boon Investigations on the lignin polymer system in enzyme-digested lamina and midrib tobacco residues using analytical pyrolysis techniques 44th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 44, Paper No. 51, 1990, p. 37. 

Historically, dietary fiber referred to iasoluble plant cell wall material, primarily polysaccharides, not digested by the endogenous enzymes of the human digestive tract. This definition has been extended to iaclude other nondigestible polysaccharides, from plants and other sources, that are iacorporated iato processed foods. Cellulose [9004-34-6] (qv) is fibrous however, lignin [9005-53-2] (qv) and many other polysaccharides ia food do not have fiberlike stmctures (see also Carbohydrates). 

Dietary fibre was defined by Hugh TroweU as the plant polysaccharides and lignin which are resistant to hydrolysis by the digestive enzymes of humans . This definition lacks chemical precision, because non-flbrous pectins and gums are also present. The term nonstarch polysaccharide (NSP) is often preferred, although the term dietary fibre still persists. Unfortunately, NSP is also not satisfactory since some starch, known as resistant or par-... 

Pew found that the residue, mainly lignin, from unground wood digested by cellulytic enzymes was insoluble in IN sodium hydroxide while the residue from finely ground wood was freely soluble 26). Also, spruce periodate lignin, normally insoluble in methyl cellosolve and in 0. N... 

The complex nature and interconnectivity of plant cell wall polymers preclude straightforward enzymatic digestion. There are dozens of enzyme families involved in plant cell wall hydrolysis, including cellulases, hemicellu-lases, pectinases, and lignin-modifying enzymes. The Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB) has classified cellulases and hemicellulases, like all enzymes, into different classes based on activity. Table 33.2 and Table 33.3, compiled from the IUBMB enzyme nomenclature database (http //www.chem.qmul.ac.uk/iubmb/ enzyme/), list the IUBMB enzyme classifications for cellulases and hemicellulases.153... 

Cell walls are biochemically rather inert with reduced digestibility to many organisms because of their complex cellulose, pectin, and lignin molecules. Callose and lignin are often accumulated at the site of infection or wounding (6,7) and form a penetration barrier. Synthesis of inhibitory proteins (e.g., lectins, protease inhibitors) or enzymes (e.g., chitinase, lysozyme, hydrolases, nucleases) that could degrade microbial cell walls or other microbial constituents would be protective, as well as synthesis of peroxidase and phe-nolase, which could help inactivate phytotoxins produced by many bacteria and fungi. These proteins are either stored in the vacuole... 

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