19F-NMR spin-spin relaxation (T2) method for characterizing volatile anesthetic bindi
19F-NMR spin-spin relaxation (T2) method for characterizing volatile anesthetic binding to proteins. Analysis of isoflurane binding to serum albumin.
Related Articles 19F-NMR spin-spin relaxation (T2) method for characterizing volatile anesthetic binding to proteins. Analysis of isoflurane binding to serum albumin. Biochemistry. 1992 Aug 11;31(31):7069-76 Authors: Dubois BW, Evers AS This paper characterizes the low-affinity ligand binding interactions of a fluorinated volatile anesthetic, isoflurane (CHF2OCHClCF3), with bovine serum albumin (BSA) using 19F-NMR transverse relaxation (T2). 19F-NMR spectra of isoflurane in aqueous BSA reveal a single isoflurane trifluoromethyl resonance, indicative of rapid exchange of isoflurane between protein-bound and aqueous (free) environments. The exchange is slow enough, however, that the chemical shift difference between bound and free isoflurane (delta omega = 0.545 ppm) contributes to the observed isoflurane T2. The contribution of delta omega to T2 can be minimized by shortening the interval between 180 degrees refocusing pulses in the Carr-Purcell-Meiboom-Gill pulse sequence used to monitor T2. Analysis of the dependence of T2 on interpulse interval additionally allows determination of the T2 (6.2 ms) and the average lifetime (tau b = 187 microseconds) of bound isoflurane molecules. By use of a short interpulse interval (less than 100 microseconds), T2 measurements can readily be used to analyze equilibrium binding of isoflurane to BSA. This analysis revealed a discrete saturable binding component with a KD = 1.4 mM that was eliminated either by coincubation with oleic acid (6 mol/mol of BSA) or by conversion of BSA to its "expanded" form by titration to pH 2.5. The binding was independently characterized using a gas chromatographic partition analysis (KD = 1.4 mM, Bmax = 3-4 sites). In summary, this paper describes a method whereby T2 measurements can be used to characterize equilibrium binding of low-affinity ligands to proteins without the confounding contributions of chemical shift.(ABSTRACT TRUNCATED AT 250 WORDS) PMID: 1643040 [PubMed - indexed for MEDLINE] Source: PubMed |
All times are GMT. The time now is 11:10 AM. |
Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
Copyright, BioNMR.com, 2003-2013