Open AccessEnzymatically Active Half‐Monomers of Acetylcholinesterase
Author(s) -
Millar David B.,
Grafius Melba A.,
Palmer David A.,
Millar Geraldine
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb03002.x
Subject(s) - acetylcholinesterase , acetylthiocholine , monomer , chemistry , dimer , enzyme , cleavage (geology) , protein subunit , ammonium sulfate , gel electrophoresis , molecular mass , stereochemistry , chromatography , polymer , biochemistry , organic chemistry , aché , biology , fracture (geology) , gene , paleontology
1 An enzymatically active 7.4‐S species of acetylcholinesterase has been isolated which has a molecular weight of 134000 ± 6%. It apparently has its origin in a Triton‐X‐100‐mediated cleavage of higher polymers of acetylcholinesterase but not from cleavage of purified 10.8‐S enzyme. The half‐monomer has a K m for acetylthiocholine almost twice that of 10.8‐S enzyme but the K i for eserine is the same. The subunit molecular weight of the 7.4‐S enzyme, as determined by sodium dodecylsulfate gel electrophoresis, is about 65000 indicating the enzyme to be a dimer. The enzyme is maximally heat stable in 0.1 M ammonium sulfate. Under certain conditions we observe a speed dependency of the sedimentation coefficient. These properties may make the half‐monomer a useful model for studying the kinetics and subunit interactions in acetylcholinesterase.