The 'back door' hypothesis for product clearance in acetylcholinesterase challenged by site-directed mutagenesis
| Autor: | C. Kronman, Arie Ordentlich, Dov Barak, Baruch Velan, Avigdor Shafferman |
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| Rok vydání: | 1994 |
| Předmět: |
Protein Conformation
Stereochemistry Gene Expression Biochemistry Active center chemistry.chemical_compound Protein structure Humans Amino Acid Sequence Binding site Codon Site-directed mutagenesis Molecular Biology Binding Sites Base Sequence biology Chemistry Mutagenesis Active site Cell Biology Acetylcholinesterase Recombinant Proteins Models Structural Kinetics Mutagenesis Site-Directed biology.protein Salt bridge |
| Zdroj: | Journal of Biological Chemistry. 269:27819-27822 |
| ISSN: | 0021-9258 |
| Popis: | The active site of acetylcholinesterase is near the bottom of a long and narrow gorge. The dimensions of the gorge and the strong electrostatic field generated by the enzyme appear inconsistent with the enzyme's high turnover rate. Consequently, a "back door" mechanism involving movement of the reaction products through a transient opening near the active center was recently suggested. We investigated this hypothesis in human acetylcholinesterase by testing mutants at key residues (Glu-84, Trp-86, Asp-131, and Val-132) located near or along the putative back door channel. The turnover rates of all mutants tested, and in particular of V132K, where the channel is expected to be sealed by salt bridge Lys-132-Glu-452, are similar to that of the wild type enzyme. This indicates that the proposed back door is not a route for product clearance from the active site gorge of acetylcholinesterase and is probably of no functional relevance to its catalytic activity. |
| Databáze: | OpenAIRE |
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