Toxicological significance of acetylcholinesterase of the housefly thorax

• Published in: Pesticide biochemistry and physiology Vol. 10; no. 3; pp. 322 - 332
• Main Authors: Steele, R.W., Maneckjee, A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.01.1979
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/0048-3575(79)90038-5

Polyacrylamide gel electrophoresis of the 100,000 g supernatant fraction of thoracic homogenates from the DDT S housefly strain separated five bands having acetylcholinesterase activity. Ferguson plots indicated that the three bands of slowest mobility constituted members of the heterologous-size isomer family described for the head enzyme. The two faster migrating bands appeared as electrophoretic artifacts of juxtaposition with a 3.6 S nonacetylcholinesterase component; in the absence of juxtaposition, a single form was characterized with identical molecular properties to the 5.3 S fundamental unit of head acetylcholinesterase. The kinetic properties of isolated forms were consonant with the molecular data and no major differences in K m values for acetylthiocholine were discovered between the thoracic and head enzymes. We suggest the preferential in vivo inhibition of thoracic acetylcholinesterase by organophosphate pesticides is unlikely the consequence of biochemical differences between the enzymes from the two regions.