Influence of the water structure on the acetylcholinesterase efficiency
Angela S. F. Ramos 1 and Simone Techert 1*
1 Max-Planck-Institut fuer biophysikalische Chemie, Goettingen, Germany
* To whom correspondence should be addressed. E-mail: stecher{at}gwdg.de.
Submitted on November 5, 2004
Revised on January 20, 2005
Accepted on 2 June 2005
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Abstract |
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ABSTRACT: We have studied the catalytic efficiency of acetylcholinesterase (AChE) in various solutions with ion-disturbed water structure in order to explore the role that the water structure plays in the substrate-enzyme encounter. The extent of water structuring in the different aqueous solutions was determined by NIR-spectroscopy. The influence of water structure on the degree of solvation and on the intramolecular mobility of AChE was investigated for different aqueous ionic solutions by small-angle x-ray scattering technique and depolarization fluorescence spectroscopy. It was found that the encounter process between AChE and acetylthiocholine (AcSCh) was promoted in solutions with less structured water. In these solutions it was also found that AChE is less solvated coinciding with higher intramolecular mobility. The found experimental results suggest that the water structure may influence the substrate-enzyme encounter process by diminishing the AChE solvation shell and may help diffusion of the substrate through the gorge by enhancing the intramolecular mobility of AChE.
Key Words:
enzymatic kinetics, fluorescence polarization, near infrared, protein, solvation dynamics, water structure
