Bacterial Catabolism of Biphenyls: Synthesis and Evaluation of Analogues

Abstract

A series of alkylated 2,3-dihydroxybiphenyls has been prepared on the gram scale by using an effective Directed ortho Metalation-Suzuki-Miyaura cross-coupling strategy. These compounds have been used to investigate the substrate specificity of the meta-cleavage dioxygenase BphC, a key enzyme in the microbial catabolism of biphenyl. Isolation and characterization of the meta-cleavage products will allow further study of related processes, including the catabolism of lignin-derived biphenyls.

Metal- and Serine-Dependent Meta-Cleavage Product Hydrolases Utilize Similar Nucleophile-Activation Strategies

“…This spectral signature was further exploited to obtain a binding isotherm, which yielded a K d value of 25 ± 1 μM and Hill coefficient of ∼1 (Figure B). The ability of LigY to bind 4-methyl-HOPDA at physiological pH indicates this compound does not readily form a lactone, in contrast to what has been proposed for DCHM-HOPDA …”

“…Accordingly, we investigated LigY’s ability to transform 4-carboxy-HOPDA and 4-methyl-HOPDA. 4-Methyl-HOPDA was produced from 5-methyl-DHB as described previously . 4-Carboxy-HOPDA was prepared by reacting 5-carboxy-DHB with PCD.…”

“…These 4-substituted HOPDAs have p K a values (∼10) much closer to DCHM-HOPDA (11.3) than to HOPDA (7.3) (Figure S1). , Analysis of the reaction mixtures by HPLC revealed that LigY catalyzed the hydrolysis of 4-carboxy-HOPDA to benzoate and CHPD (Figure S4). By contrast, LigY did not detectably transform 4-methyl-HOPDA.…”

“…All reagents were of analytical grade unless otherwise noted. 2,2′,3-Trihydroxy-3′-methoxy-5,5′-dicarboxybiphenyl (OH-DDVA), 5-methyldihydroxybiphenyl (DHB), and 5-carboxy-DHB were synthesized as described previously . Water for buffers was purified in a Barnstead Nanopure Diamond system to a resistance of at least 18 MΩ.…”

“…The pyridinal derivative of 4-carboxy-HOPDA was prepared by treatment of enzymatically prepared 4-carboxy-HOPDA with ammonium carbonate (0.1 M), acidification with 1% (v/v) glacial acetic acid, and passage through a 0.22 μm syringe-driven filter . The samples were resolved on an Agilent 1100 series HPLC unit equipped with an ACE Excel 2 C18-PFP (50 × 2.1 mm) column with a gradient of formic acid and acetonitrile . Mass spectra were measured on an Applied Biosystem Qstar mass spectrometer.…”