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Essential arginine residue in acetylcholinesterase from Torpedo californica
Author(s) -
Mü H.,
Sund H.
Publication year - 1980
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(80)80272-9
Subject(s) - stereochemistry , chemistry , philosophy , humanities , library science , computer science
Acetylcholinesterase (EC 3.1.1.7) has been the subject of many kinetic studies [2]. However, neither the kinetic mechanisms nor the ammo acid residues involved in substrate binding with the exception of the activated serine residue [2] could be elucidated completely from these studies. From kinetic and chemical modification data histidine [3] and tyrosine [4] residues have been proposed to have functional roles in the catalytic mechanism and are located near or within the active centre of the enzyme. A carboxyl residue different from that within the anionic part of the active centre was localized [5] within one of the peripheric anionic sites [2]. But nothing is known about the function of the basic amino acids like lysine and arginine. Since lysine as well as arginine are able to bind negatively charged substrates and also stabilize conformations we have investigated the role of basic amino acids in the catalytical mechanism of acetylcholinesterase by chemical modification of the arginine residues with both butanedione and phenylglyoxal, which are argininespecific reagents. The chemical modifications were also carried out in the presence of the effecters N-methylpyridinium-2-aldoxime iodide, flaxedil, edrophonium, hexamethonium and decamethonium, because Changeux [6] observed an activation effect of peripheric bound ligands, probably caused by allosteric effects [4,7]. The location of the modified arginine residues and their participation in the catalytic mechanism is discussed.