Hydrogen exchange kinetics and dynamic structure of erabutoxin B from 1H NMR and infrared spectrometry

Abstract

As an approach to the conformational dynamics of erabutoxin b, the 1H 2H exchange kinetics have been measured in 2H 2O at 30°C, pH 4.75, by means of infrared spectrometry and high resolution 1H NMR. With a solvent exposure coefficient higher than 10 −3 for 90 % of its backbone amide hydrogens, erabutoxin b shows a relatively large solvent accessibility: this is consistent with an open and/or flexible molecule. 17 backbone hydrogens and 9 side chain hydrogens exchange slowly. These results compare fairly well with the number of potential hydrogen bonds recently reported from X-ray analysis.