Solution structure and membrane-binding property of the N-terminal tail domain of human annexin I

The conformational preferences of AnxI(N26), a peptide corresponding to res idues 2-26 of human annexin I, were investigated using CD and NMR spectrosc opy, CD results showed that AnxI(N26) adopts a mainly a-helical conformatio n in membrane-mimetic environments, TFE/water and SDS micelles, while a pre dominantly random structure with slight helical propensity in aqueous buffe r. The helical region of AnxI(N26) showed a nearly identical conformation b etween in TFE/water and in SDS micelles, except for the orientation of the Trp-12 side-chain, which was quite different between the two. The N-termina l region of the AnxI(N26) helix showed a typical amphipathic nature, which could be stabilized by the neighboring hydrophobic cluster. The helical sta bility of the peptide in SDS micelles was increased by addition of calcium ions. These results suggest that the N-terminal tail domain of human annexi n I interacts with biological membranes in a partially calcium-dependent ma nner. (C) 2000 Federation of European Biochemical Societies. Published by E lsevier Science B,V, All rights reserved.