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To address biophysical principles and lipid interactions that underlie the properties of membrane proteins, modifications that vary the neighbors of tryptophan residues in the highly dynamic transmembrane helix of GW^4,20ALP23 (acetyl‐GGAW⁴A(LA)₆LAW²⁰AGA‐amide) were examined using deuterium NMR spectroscopy. It was found that L^5,19GW^4,20ALP23, a sequence isomer of the low to moderately dynamic GW^5,19ALP23, remains highly dynamic. By contrast, a removal of W4 to produce F^4,5GW²⁰ALP23 restores a low level of dynamic averaging, similar to that of the F^4,5GW¹⁹ALP23 helix. Interestingly, a high level of dynamic averaging requires the presence of both tryptophan residues W4 and W20, on opposite faces of the helix, and does not depend on whether residue 5 is Leu or Ala. Aspects of helix unwinding and potential oligomerization are discussed with respect to helix dynamic averaging and the locations of particular residues at a phosphocholine membrane interface.