Two-dimensional measurement of proton T1rho relaxation in unlabeled proteins: mobility changes in alpha-bungarotoxin upon binding of an acetylcholine receptor peptide.

ABSTRACT: A method for the measurement of proton T(1)(rho) relaxation times in unlabeled proteins is described using a variable spin-lock pulse after the initial nonselective 90 degrees excitation in a HOHAHA pulse sequence. The experiment is applied to alpha-bungarotoxin (alpha-BTX) and its complex with a 25-residue peptide derived from the acetylcholine receptor (AChR) alpha-subunit. A good correlation between high T(1)(rho) values and increased local motion is revealed. In the free form, toxin residues associated with receptor binding according to the NMR structure of the alpha-BTX complex with an AChR peptide and the model for alpha-BTX with the AChR [Samson, A. O., et al. (2002) Neuron 35, 319-332] display high mobility. When the AChR peptide binds, a decrease in the relaxation times and the le

SUBMITTER: Samson AO 

PROVIDER: S-EPMC2597414 | biostudies-literature | 2005 Aug

REPOSITORIES: biostudies-literature