NMR analysis of secondary structure and dynamics of a recombinant peptide from the N-terminal region of human erythroid alpha-spectrin

We have studied the nuclear magnetic resonance solution secondary structure of the N-terminal region in human erythroid alpha -spectrin using a recomb inant model peptide of alpha -spectrin consisting of residues 1-156, Pulsed field gradient diffusion coefficient measurements show that the model pept ide exists as a monomer under the solution conditions used, The first 20 re sidues are in a random coil conformation, followed by a helix of 25 residue s and then a random coil segment before the next helix. The random coil nat ure of this linker was confirmed by the presence of fast internal motion fr om N-15 relaxation measurements. The second, third and fourth helices are t hought to form the triple helical bundle structural domain, consistent with previous studies. Our study shows that the N-terminal region of alpha -spe ctrin prior to the first structural domain forms a well behaved helix witho ut its beta -spectrin partner. (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V, All rights reserved.