Enzymes lignin decomposition

In order to eluddate the mechanism of the further transformations of the primary lignin decomposition products including the cleavage reactions, we synthesized some of the important primary products labelled with Cu and introduced these into the cultures of fungi or enzymes. Thus, it could be shown, for example, that the breakdown of the side chain of ferulic acid occurs at the double bond vanillic acid is found. During polymerization in the presence of phenoloxidases, in the case of carboxyl-labelled ferulic acid, about 60% of the activity is split off as Cli02. The polymers labelled in the 2 and 3 position in the side chain or in the methoxyl group contain the whole applied activity. 

In the following discussion, we have assumed that wood decay is due to the concerted action of the individual enzyme systems responsible for cellulose, hemicellulose, and lignin decomposition. 

Many past studies on the enzymes of lignin decomposition focused on phenol-oxidizing enzymes, such as laccase and peroxidase, produced by white-rot fungi. It is unlikely, however, that this type of activity is important in structural decomposition (33), although the enzymes may have some other role in lignin decomposition (28). 

Gottlieb, S., and J. H. Geller Enzymic Decomposition of Lignin. Science... 

During decomposition most of the nitrogen is immobilized initially, at least, in microbial cells, which in turn are broken down. In the process, a considerable portion of the nitrogen reacts with phenols, quinones, and other ring compounds derived from lignin, or synthesized by microorganisms, to form humic substances, some of which are heterocyclic. Amino acids and ammonia are subject to such chemical reactions, that may be catalyzed by microbial enzymes. In soils with 2 1 clay minerals any ammonia that is formed is also subject to fixation in the clay lattice (see Chapter 8 and 11). 

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