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. 2003 May;185(9):2944–2951. doi: 10.1128/JB.185.9.2944-2951.2003

TABLE 2.

Transformation of chlorosubstituted 2,3-dihydroxybiphenyls by 2,3-dihydroxybiphenyl 1,2-dioxygenases

Biphenyl congener Dominantly formed 2,3-dihydroxybiphenyl λmax (nm)g Relative activity (%) of enzyme (strain)a
BphC1 (P6) BphC2 (P6) BphC3 (P6) DbfB (RW1) BphC (LB400)
2-Chloro 2′-Chloroa 392 ± 2 3.5 57 50 3 1.2
3-Chloro 3′-Chloroa 434 ± 2 64 71 95 47 36
4-Chloro 4′-Chloroa 437 ± 2 61 84 77 65 51
2,3-Dichloro 2′,3′-Dichloroc,d 392 ± 2 1.5 25 57 0.5 1
2,4-Dichloro 2′,4′-Dichloroc,d 392 ± 2 6.5 33 63 0.8 1.1
2,5-Dichloro 2′,5′-Dichloroc,d 392 ± 2 4 5.5 27 1.8 2.0
3,4-Dichloro 3′,4′-Dichlorod 440 ± 2 31 59 49 28 32
3,5-Dichloro 3′,5′-Dichlorod 436 ± 2 51 15 49 12 37
2,3′-Dichloro 2′,5-Dichlorob 395 ± 5 0.4 3 5 0.3 1.2
3,3′-Dichloro 3′,5-Dichloroe 412 ± 5 3.5 2 8 4.5 3
2,4′-Dichloro 2′,4-Dichloroa 396 ± 5 7 6 14 4 0.5
3,4′-Dichloro 4′,5-Dichloroa 415 ± 5 1.5 4 9 2 4
2,3,4-Trichloro 2′,3′,4′-Trichloroc,d 392 ± 2 1.8 2.5 9 0.2 0.5
2,3,5-Trichloro 2′,3′,5′-Trichloroc,d 393 ± 2 1.2 2 21 0.2 2.5
2,4,5-Trichloro 2′,4′,5′-Trichloroc,d 393 ± 2 2.5 0.9 3 1.1 1.5
3,4,5-Trichloro 3′,4′,5′-Trichlorod 420 ± 5 26 11 7 14 12
3,4,2′-Trichloro 3′,4′,5-Trichlorof 434 ± 2 29 11 9 11 17
a

The identity of the dihydroxybiphenyl dominantly formed was deduced from data in the literature (28, 44). R. globerulus P6 biphenyl dioxygenase was shown to produce exclusively or dominantly one dioxygenation product (>95%).

b

R. globerulus was shown to dominantly form 2′,5-dichlorodihydroxybiphenyl (80%) and minor amounts of 3′,5-dichlorodihydroxybiphenyl (44).

c

The absorption maximum of the ring cleavage product (392 to 396 nm) indicates the presence of a chlorosubstituent at the ortho position of the aromatic ring (37), and thus, the BphA-mediated dioxygenation occurred on the unsubstituted aromatic ring.

d

The BphA-mediated dioxygenation reaction on di- or trichlorobiphenyls with substitutions on one aromatic ring can be assumed to have occurred on the unchlorinated ring, as proven for monochlorinated biphenyls (28).

e

As neither dechlorination nor 4,5-dioxygenation has been reported for R. globerulus P6 BphA, a dominant 5,6-dioxygenation can be assumed.

f

The absorption maximum of the ring cleavage product (434 nm) indicates the absence of a chlorosubstituent at the ortho position of the aromatic ring (37), and thus, the BphA-mediated dioxygenation occurred on the less chlorinated aromatic ring.

g

Mean±standard error.