Cysteine conjugate beta-lyase activity in three species of parasitic helminth

Living organisms employ a variety of metabolic pathways when detoxifying xe nobiotic compounds, including the formation of cysteine S-conjugates via gl utathione conjugation. However, cysteine conjugate beta-lyase (CCBL) cataly sed beta-cleavage, of certain cysteine conjugates, is known to cause cytoto xicity. This study represents the first investigation into the expression o f CCBL and other associated enzymes in helminth species. A survey of the th ree major groups of parasitic helminths [cestodes (Moniezia expansa), digen eans (Fasciola hepatica) and nematodes (Necator americanus, Heligmosomoides polygyrus)] has been made. The presence of CCBL enzymes within Moniezia ex pansa, Necutor americanus and Heligmosomoides polygyrus has been establishe d. Each species was screened for gamma-glutamyl transpeptidase activity and transaminase activity towards L-aspartate, L-alanine, L-albizziin and L-ph enylalanine. Aspartate and alanine aminotransferase activity were detected in all four species tested, gamma-Glutamyl transpeptidase activity was only detected in Moniezia expansa and Necator americanus. (C) 1999 Published by Elsevier Science Ltd on behalf of the Australian Society for Parasitology. All rights reserved.