Hydrogen exchange from the transbilayer hydrophobic peptide of glycophorin reconstituted in lipid bilayers.

The hydrophobic transbilayer peptide of erythrocyte glycophorin has been purified following exchange of tritium into the backbone amides, and reconstituted in egg phosphatidylcholine micelles. Analysis of tritium exchange from the backbone amides of the membrane-reconstituted peptide shows that about two of the amides are virtually non-exchangeable, about 10 are slowed by factors of 10(7) relative to free amides in unstructured water soluble peptides and the remainder of the amides (about 20) have slowing factors of less than 1000. These classes of amides are proposed to reflect the stability of the peptide with respect to hydrogen bond breaking fluctuations and the accessibility of the amides to exchange catalysts in different regions of the bilayer.