Aromatic ring cleavage

Buchan A, LS Collier, EL Neidle, MA Moran (2000) Key aromatic-ring-cleavage enzyme, protocatechuate 3,4-dioxygenase, in the ecologically important marine Roseobacter lineage. Appl Environ Microbiol 66 4662-4672. 

Lendenmann U, JC Spain (1996) 2-aminophenol 1,6-dioxygenase a novel aromatic ring cleavage enzyme purified from Pseudomonas pseudoalcaligenes JS 45. J Bacteriol 178 6227-6232. 

Umezawa T, Fliguchi T (1987) Mechanism of aromatic ring cleavage of h-O-4 lignin substructure models by lignin proxidase. FEBS Lett 218 255-260... 

Other steps such as desulfonation may occur under anaerobic conditions [32], although some authors have shown resistance of the aromatic ring cleavage in the natural medium [33,34]. Other authors,... 

Not known possibly from aromatic ring cleavage... 

Fig. 15.6 Aromatic ring cleavage degradation pathways of endocrine disruptor nonylphenol isomers by Sphingomonas sp. strain TTNP3. (Corvini et al. 2006)...

Figure 3. Mechanism for aromatic ring cleavage of 3-0-4 dimer by-lignin peroxidase/H202 system. and 0 0 of H2 0 and 02, respectively. LP lignin peroxidase.

Figure 9. Molar yields, obtained after 20 minutes at pH 3.0 with 0.13 units mL lignin peroxidase in the presence of H2O2 and veratryl alcohol, of C -Cg, B-O-4 and aromatic ring cleavage products from 4.ethoxy-3-methoxyphenylgfycerol-B-syringyl ether moieties in dehydrogenative copolymer of conifery] alcohol and 4.ethoxy 3-methoryphet lgfycerol-B-syringaresinol (54).

Figure 5. The enzymatic oxidation of a synthetic / -0-4 lignin model substrate and fungal secondary metabolites. Both undergo Ca-C/ bond and aromatic ring cleavages in reactions catalyzed by the same ligninase in the presence of H2O2.

The phenylalanine-cinnamate pathway of the white-rot fungus P. chrysosporium is linked to lignin biodegradation by two reactions, i.e., by both Ca-C/3 bond and aromatic ring cleavages. These represent the... 

Also depicted in Figure 5 are the aromatic ring cleavage pathway and the degradation of Ci, C2 and C3 fragments derived from the phenylpropane side chain of the lignin building blocks. 

Aromatic Ring Cleavage of Nonphenolic 0-0-4 Lignin Substructure Model Compounds and Veratryl Alcohol by Lignin Peroxidase. 

Aromatic Ring Cleavage of Phenolic 0-0-4 Substructure Model Compounds by Laccase. When vanillyl alcohol was used as a substrate, only biphenyl formation (C5-C5 linked) occurred and no evidence for the formation of any ring-opened products was obtained (26). Hence, we also examined the effect of laccase on the sterically hindered 4,6-di-<-butylguaiacol substrate 50, as it would be unlikely to undergo such free-radical coupling reactions... 

Figure 8. Aromatic ring cleavage of nonphenolic / -0-4 model compounds 31-33 by lignin peroxidase.

Figure 13. Proposed mechanisms for aromatic ring cleavage of 4,6-di-t-butylguaiacol 50 by laccase.

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