Fluorescence And Nmr-Studies Of The Binding Of Cholinergic Fluorescent-Probes To Horse Serum-Cholinesterase

Narayanan, R and Balaram, P (1981) Fluorescence And Nmr-Studies Of The Binding Of Cholinergic Fluorescent-Probes To Horse Serum-Cholinesterase. In: International Journal Of Peptide And Protein Research, 17 (2). pp. 170-180.

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Abstract

The interaction of the cholinergic fluorescent probes, 1-(5-dimethyl-aminoaphthalene-1-sulfonamido) ethane-2-trimethylammonium perchlorate, 1-(5-dimethylaminonaphthalene-1-sulfonamido) pentane-5-trimethylammonium tartarate and 1-(5-dimethylaminonaphthalene-1-sulfonamido) decane-10- trimethylammonium tartarate with horse serum cholinesterase has been examined by fluorescence and n.m.r. methods. Fluorescence titrations show binding of the decane derivative to two sites on the protein whereas the lower homologs bind largely to one site. Active site inhibitors like curbamylcholine and decamethonium abolish binding of the decane derivative to the high affinity site. The inhibitors are largely without effect on the binding of the lower homologs. N.m.r. studies clearly establish immobilization of both ends of the molecule on binding in the case of the decane derivative, whereas in the lower homologs the dimethylamino group on the naphthalene ring is significantly more affected in the presence of enzyme. The probes are effective inhibitors of the enzyme with the decane derivative being two orders of magnitude more effective than its lower homologs. Based on the n.m.r., fluorescence and inhibition studies, a model for probe binding to the enzyme is advanced. It appears that the decane derivative binds with high affinity to the catalytic anionic site while the lower affinity site is assigned to a peripheral anionic site. The lower homologs probe only the peripheral site. A comparison of fluorescence, n.m.r. and inhibition studies with acetylcholinesterases from electric eel and bovine erythrocytes is presented.

Item Type:	Journal Article
Publication:	International Journal Of Peptide And Protein Research
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article belongs to John Wiley and Sons.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	21 Aug 2009 08:49
Last Modified:	19 Sep 2010 05:41
URI:	http://eprints.iisc.ac.in/id/eprint/22365

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