Clutathione S-transferases (CST) from larvae of the sugarcane borer, Diatraea Saccharalis (F.) and the Mexican rice borer, Eareuma laftini (Dyar), were characterized. Apparently homogeneous CST isoenzymes from the larvae of both species were purified with CSH-affinity chromatography and isoelectric focusing. E. laftini had higher CST activity (31.12 units/g wet weight of tissue) compared with D. saccharalis (24.8 units/g wet weight of tissue). The CST isoenzyme of D. saccharalis with a pi value of 9.3 was a dimer of two identical subunits (M, 25,000), whereas the CST isoenzyme with a pi value of 8.0 was a heterodimer with subunit M, values of 25,000 and 27,000. The CST isoenzymes of E. laftini with pI values of 9.7 and 7.7 were homo dimers of subunits with M, values of 25,000 and 26,000, respectively. However, the CST isoenzyme with a pI value of 5.3 was a heterodimer of subunits having M, values of 26,000 and 27,000. Peptide fingerprint analysis by SV-8 protease digestion revealed primary structural differences in these isoenzymes. The N-termini of all CST isoenzymes from both the species of larvae were blocked. Substrate specificities and kinetic properties of the purified CSTs from both the species have been described. The low Km and high Vm" values toward l-chloro-2,4-dinitrobenzene of CST enzymes isolated from both D. saccharalis and E. laftini indicate that these enzymes have a high affinity for electrophilic substrates compared with most human CSTs.
Document Type: Research Article
Publication date: October 1, 1991
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.