Lignins complex with iron

Because the three-dimensional structures of the peroxidase, its reductant cytochrome c, and the complex of the two (Fig. 16-9) are known, cytochrome c peroxidase is the subject of much experimental study. Other fungal peroxidases, some of which contain manganese rather than iron, act to degrade lignin (Chapter 25).218 A lignin peroxidase from the white wood-rot fungus Phanerochaete chrysosporium has a surface tryptophan with a specifically hydroxylated C(3 carbon atom which may have a functional role in catalysis.2183 0... 

It is likely that iron and other heavy metal ions are present in the raw water used in the kraft process, and possibly the kraft lignin is complexing these metals with the formation of color. 

Another sample of enzymatic lignin freshly prepared from Hurricane-pulverized wood was suspended in 0.1 M EDTA and stored at 4°C for one week. This treatment also enhanced the adsorption of nitrosamine (Figure 2). It therefore appears that ion exchange of heavy metals, notably iron, by complex formation with EDTA enhances the adsorption of nitrosamine on enzymatic lignin. Systematic control of the heavy metal ions in enzymatically prepared lignins is a necessary feature of future studies. 

Biosensitisers and photosensitisers are nsed to obtain PE with predictable life times. Iron complexes Fe(iii)-acetylacetonate, Fe(iii)-2-hydroxy-methylacetophenoneoxime, transition metal (Co, Ni, Cr, Zn)-N,N -diethyldiselenocarbamates or other metallic complexes, and blends with natural polymers (starch, cellulose, lignin, proteins) are mostly used. 

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