STUDIES ON CYSTEINE CONJUGATE BETA-LYASE AND THIOL S-METHYLTRANSFERASE IN INSECTS

Cysteine conjugate beta-lyase activity was demonstrated in the cuticle of M. sexta and H. virescens and was present in the cytosolic fractio n from both of these species. Enzymatic activity was significantly dec reased following each molt of the larvae and then increased until the start of the next instar. Beta-Lyase activity increased for 20 h after eclosure in the adult and the highest larval activity was measured in the late fifth instar. The insect enzyme appears to be less sensitive to (aminooxy)acetic acid, a cysteine conjugate beta-lyase inhibitor, than was reported for the rat renal enzyme. Thiol S-methyltransferase activity was also localized in the cuticle of both insect species but was present in both the microsomal and cytosolic fractions.