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Updated: Jun 15, 2026

Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
Influence of amino acid side chains on apparent selective opening of cyclic b5 ions
Samuel Molesworth1, Sandra Osburn, Michael Van Stipdonk
1Department of Chemistry, Wichita State University, Wichita, Kansas 67260-0051, USA.
Abstract:
In this study, the possible influence of acidic, basic, and amide side chains on the opening of a putative macrocyclic b ion (b(5)(+)) intermediate was investigated. Collision induced dissociation (CID) of b(5) ions was studied using a group of hexapeptides in which amino acids with the side chains of interest occupied internal sequence positions. Further experiments were performed with permuted isomers of glutamine (Q) containing peptides to probe for sequence scrambling and whether the specific sequence site of the residues influences opening of the macrocycle. Overall, the trend for (apparent) preferential/selective opening of the cyclic b(5)(+), presumably due to the side chain, followed by the loss of the amino acid with active side group is: Q > K > D > N approximately E.
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