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Characterization of Acetylcholinesterase purified from the Lesser Grain Borer, Rhyzopertha dominica (Coleoptera: Bostrichidae)
Author
Guedes, R. N. C.
Zhu, K. Y.
Kambhampati, S.
Dover, B. A.
Institutions
Abstract
Acetylcholinesterase (AChE, EC 3.1.1.7) purified from the lesser grain borer (Rhyzopertha dominica) was significantly inhibited by higher concentrations of the substrates acetylthiocholine (ATC), acetyl-(β-methyl) thiocholine (AβMTC) and propionylthiocholine (PTC). The efficiency of AChE for hydrolyzing different substrates was ATC > AβMTC > PTC > S-butyrylthiocholine. The enzyme activity was completely inhibited by 10−5 M eserine or BW284C51, but was only partially inhibited by ethopropazine at the same concentration. These results confirmed that the purified enzyme was an typical insect AChE. Non-denaturing and SDS polyacrylamide gel electrophoresis (PAGE) showed only one major molecular form in the purified AChE with a molecular weight of about 107,000 prior to reduction and about 56,000 after reduction, suggesting the homodimer of AChE linked with disulfide bonds.