Tryptophane as a Rotating Flap: Omega Loop Dynamics in Acetylcholinesterase
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| Year of publication | 2007 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Back door to the active site of acetylcholinesterase (AChE) and its involvement in the catalytic cycle of this enzyme are a really controversial subject. The back door could explain the contrast of a very high AChE catalytic efficiency and the narrow and long access to the active site located in the middle of the protein. Back door could facilitate the diffusion of reaction products - choline or acetic acid after the cleavage of acetylcholine. Back door was seen only in a molecular dynamics of AChE, but for a very short times and its existence was not confirmed experimentally. Herein we present a molecular dynamics of AChE, where the back door opening appears on a nanosecond time scale. We also present a molecular dynamics of AChE, where the back door do not open at all, or where large conformational changes of AChE omega loop occur instead of back door opening events. The differences in the AChE dynamical behaviour are caused by different protonation states of two glutamate residues located on bottom of the active site gorge. The two glutamates (Glu202 and Glu450) with addition of Glu334, located in their proximity as a part of catalytic triad, can strengthen the negative electric field on the bottom of the gorge, when unprotonated, or weaken the field, when protonated, or their charge is compensated by a sodium ion. Other alternative ways to AChE active site (side door) and the overall porosity of omega loop are also discussed. |
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