Glucose and sulfate conjugations of phenol, β-naphthol and 3-hydroxybenzo[a]pyrene by the American lobster ( Homarus americanus)

Abstract

Little is known of the potential for conjugation of phenolic compounds by lobsters. Studies were designed to determine the ability of American lobster tissues to conjugate the phenolic compounds phenol, β-naphthol and 3-hydroxybenzo[a]pyrene (3-OH BaP). Aryl sulfotransferase (ST) activity was present in the cytosolic fraction of the antennal gland (AG), but not hepatopancreas (HP), whereas UDP-glucosyltransferase (UDPGT) activity was found in musomal fractions of both AG and HP. We observed differences between male and female lobsters in their ability to conjugate phenols. For example, in males the apparent K m for PAPS of AG β-naphthol ST was 9.0 ± 4.2 μM (mean ± SD, n = 5) and V max was 77 ± 7 pmol/min/mg protein, whereas in females K m was 62 ± 3 μM ( n = 3) and V max was 254 ± 92 pmol/min/mg protein ( P < 0.05). The β-naphthol UDPGT exhibited different pH optima in HP (10.5) and AG (7.5) musomes, suggesting that more than one form of β-naphthol UDPGT exists in the American lobster. With few exceptions, K m values for the phenolic substrates were in the μM range for both UDPGT and ST, whereas K m values for the cosubstrates were lower for PAPS than for UDP-glucose.