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Molecular Properties of Drosophila Acetylcholinesterase
Author(s) -
Zingde S.,
Rodrigues V.,
Joshi S. M.,
Krishnan K. S.
Publication year - 1983
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1983.tb00818.x
Subject(s) - tetramer , acetylcholinesterase , dimer , chemistry , sephadex , enzyme , monomer , electrophoresis , protein subunit , biochemistry , molecular mass , chromatography , organic chemistry , polymer , gene
Two distinct classes of acetylcholinesterase (AChE) from the fruit fly Drosophila melanogaster are reported: a soluble species that shows heterogeneity of forms and a particulate species. The subunit composition of the particulate enzyme was studied using the active site label [ 3 H]diisopropylfIuorophosphate. Comparison of the electrophoretic patterns on nondenaturing gels using the activity stain and the active site label shows that the label is specific to AChE. The smallest active site‐containing subunit of the enzyme is a monomer of —60,000 daltons MW. Two such units are linked by disulphide bonds to produce a dimer of about 110,000 daltons. Another monomeric form of MW —64,000 daltons, although present, does not participate in the dimerisation. The particulate enzyme when solubilised exists as a 9–10S species as determined by sucrose gradient centrifugation. This species has a MW > 200,000, as shown by its behaviour on a coarse‐bead Sephadex‐G200 column. Electrophoretic analysis suggests a MW of nearly 250,000 daltons for this form. Thus, this species is likely to be a tetramer. One possibility is that this tetramer is made up of two units of 64,000 daltons each and a dimer of 110,000 daltons. Preliminary data on mutant enzymes that support such a possibility are also presented.