Author/Editor		Nachon, F; Stojan, J; Fournier, D
Title		Insights into substrate and product traffic in the Drosophila melanogaster acetylcholinesterase active site gorge by enlarging a back channel
Type		članek
Source		FEBS J
Vol. and No.		Letnik 275, št. 10
Publication year		2008
Volume		str. 2659-64
Language		eng
Abstract		To test a product exit differing from the substrate entrance in the active site of acetylcholinesterase (EC 3.1.1.7), we enlarged a channel located at the bottom of the active site gorge in the Drosophila enzyme. Mutation of Trp83 to Ala or Glu widens the channel from 5 A to 9 A. The kinetics of substrate hydrolysis and the effect of ligands that close the main entrance suggest that the mutations facilitate both product exit and substrate entrance. Thus, in the wild-type, the channel is so narrow that the 'back door' is used by at most 5% of the traffic, with the majority of traffic passing through the main entrance. In mutants Trp83Ala and Trp83Glu, ligands that close the main entrance do not inhibit substrate hydrolysis because the traffic can pass via an alternative route, presumably the enlarged back channel.
Descriptors		DROSOPHILA MELANOGASTER ACETYLCHOLINESTERASE BINDING SITES MUTAGENESIS, SITE-DIRECTED ACYLATION ACETYLCHOLINE KINETICS