conjugates were separated on RP-18F254s TOVeTSe phase TLC plates with fluorescent

indicator (Merck, Darmstadt, Germany) using methanol:water (80:20). For TCPM,

Whatman KClsF reverse phase 200 Clm TLC plates with fluorescent indicator in

conjunction with a developing solvent system consisting of methanol:water:0.28 M PIC-

A (40:60:1.9 by volume) were employed. Electronic autoradiography (Packard Instant

Imager, Meriden, CT) was used to identify and quantify the radioactive bands separated

on the TLC plate. The counts representing the substrate sulfate conjugate products were

expressed as a fraction of the total radioactivity determined by scintillation counting, thus

enabling the radioactivity due to the substrate conjugate to be accurately determined.

 The identity of the conjugate of TCPM as a sulfate ester was verified by studying

its sensitivity to sulfatase. Polar bear cytosol (0.5 mg) was incubated for 75 minutes with

or without 200 CLM TCPM. The incubation was terminated, and the product extracted into

ethyl acetate as above. The ethyl acetate was evaporated to dryness and dissolved in 0.25

mL of Tris buffer, pH 7.5, containing 0 or 0.08 units of sulfatase. Following an overnight

incubation at 35oC, the reaction was stopped by the addition of methanol and the tubes

were centrifuged. The supernatants were evaporated to dryness, reconstituted in methanol

and analyzed by TLC as described above.

UDP-Glucuronosyltransferase Assay. The reaction mixture for detecting the

glucuronidation of 3-OH-B[a]P by polar bear liver microsomes consisted of 0. 1 M Tris-

HCI buffer (pH 7.6), 5 mM MgCl2, 0.5% Brij-58, UDPGA (4 mM), 5 Clg polar bear

hepatic microsomal protein, and 3-OH-B[a]P in a total reaction volume of 500 CIL. The

substrate, 3-OH-B[a]P in methanol, was blown dry under N2 in the dark in a tube to

which, after complete evaporation, a premixed solution of microsomal protein and Brij-