Transient kinetics of the acetylcholinesterase catalyzed hydrolysis of N-methylindoxyl acetate.
An experimental study has been made of the kinetics of the hydrolysis of N-methylindoxyl acetate catalyzed by electric-eel acetylcholinesterase, both in the steady state and the pre-steady statemstopped-flow and temperature-jump experiments revealed a fast transient and a slow one. The fast transient is correlated with the conventional mechanism E+A in equilibrium EA yields X-yieldsEA' YIELDS E+Y. The slow transient is attributed to conformational changes involving E or EA. Analysis of it revealed two exponential terms of the form e- minus lambda t, and the two lambda values were obtained over the temperature range 5Yand 25Ydegrees C. The results are interpreted in terms of two alternative mechanisms; in one, the enzyme undergoes a conformational change before it adds on the substrate molecule; in the other, the conformational change occurs after the substrate addition. Both mechanisms may be involved, but the results exclude a concerted mechanism in whivh the conformational change occurs concurrently with the addition of substrate. Kinetic parameters (delta S not equal to and E) are obtained for this conformational change and for the conversion of EA into EA'+X.[1]References
- Transient kinetics of the acetylcholinesterase catalyzed hydrolysis of N-methylindoxyl acetate. Sadar, M.H., Laidler, K.J. Can. J. Biochem. (1975) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
