Phosphorescence and ODMR study of the binding interactions of acetylcholine receptor alpha-subunit peptides with alpha-cobratoxin. |
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Authors: | A E Tringali S F Pearce E Hawrot H C Brenner |
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Institution: | Department of Chemistry, New York University, NY 10003. |
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Abstract: | Optical detection of magnetic resonance (ODMR) and phosphorescence spectroscopy have been applied to synthetic peptides derived from the alpha-subunit of the nicotinic acetylcholine receptor of Torpedo californica and their complexes with alpha-cobratoxin (CBTX). The CBTX Trp phosphorescence is strongly quenched by the proximal disulfide linkage, while the emission wavelengths and ODMR frequencies of the 18-mer alpha 181-198 indicate a more hydrophobic Trp environment than in the 12-mer alpha 185-196. Binding to CBTX produces a subtle increase in the hydrophobicity of the Trp environment for the peptides, in qualitative agreement with a recently proposed binding model, in which a receptor Trp residue interacts strongly with a hydrophobic cleft of the toxin. |
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