FIG. 4.

Formation and further conversion of unstable extradiol cleavage products. Enzymes: BphA, biphenyl 2,3-dioxygenase; BphC, 2,3-dihydroxybiphenyl 1,2-dioxygenase. (A) Formation and further conversion of 2,3,2′-trihydroxybiphenyl from 2,2′-dihydroxybiphenyl. Compounds: 1, 2,2′-dihydroxybiphenyl; 2, 2,3,2′-trihydroxybiphenyl; 3, 2-hydroxy-6-(2-hydroxyphenyl)-6-oxo-hexa-2,4-dienoic acid; 4, 2-hydroxy-3-(4-oxo-chroman-2-yl)-acrylic acid. (B) Formation and further conversion of 2,3,2′-trihydroxydiphenylether from DBD. Compounds: 1, DBD; 2, 2,3,2′-trihydroxydiphenylether; 3, 2-hydroxy-hexa-2,4-diene-dioic acid 6-(2-hydroxyphenyl) ester; 4, 6-hydroxy-6-(2-hydroxyphenoxy)-6H-pyran-2-carboxylic acid; 5a, 2-pyrone-6-carboxylic acid; 5b, catechol; 6, 2-hydroxymuconic semialdehyde.