(James and Rowland-Faux, 2003). This may help to explain the persistence of these

compounds.

 Hypothesis

 The glucuronidation kinetics of a series of potentially toxic p-OH-PCBs by channel

catfish liver and proximal intestine is influenced by the structural arrangement of the

chlorine substituents around the biphenyl ring.

 Methodology

 Chemicals. A total of 14 substrates were used in this study (Figure 4-1). The

nomenclature of the OH-PCBs is based on the recommendations of Maervoet and co-

workers (2004).

 The following substrates (Catalog no. in parentheses) were purchased from

Accustandard (New Haven, CT): 4-OHCB2 (1003N), 4-OHCBl4 (2004N), 4'-OHCB69

(4008N), 4'-OHCB72 (4009N), 4'-OHCB106 (5005N), 4'-OHCBll2 (5006N), 4'-

OHCBl21 (5007N), 4'-OHCBl59 (6001N), and 4'-OHCBl65 (6002N). The compounds

4'-OHCB35, 4-OHCB39, 4'OHCB68, 4'-OHCB79 were synthesized by Suzuki-coupling

(Lehmler and Robertson, 2001; Bauer et al., 1995). The 4-hydroxy biphenyl (4-OHBP)

was purchased from Sigma (St.Louis, MO). 14C-UDPGA (196 CICi/Clmol) was obtained

from PerkinElmer Life and Analytical Sciences (Boston, MA). The 14C-UDPGA was

diluted with unlabelled UDPGA to a specific activity of 1.5-5 CICi/Clmol for use in

enzyme assays. PIC-A (tetrabutylammonium hydrogen sulfate) was obtained from

Waters Corp. (Milford, MA). Other reagents were the highest grade available from Fisher

Scientific (Atlanta, GA) and Sigma.