¹H NMR and CD secondary structure analysis of cell adhesion promoting peptide F-9 from laminin

A heparin binding, cell adhesion promoting domain, termed peptide F-9, from the B1 chain of human laminin, residues 641 to 660, i.e. RYVVLPRPVCFEKGMNYTVR, has been investigated by ¹H NMR (500 MHz) spectroscopy and CD spectropolarimetry. While small linear peptides in water solution normally exist in a number of fluctuating conformational states, CD data analysis of peptide F9 indicates the existence of some preferred average structural populations consisting of about 30% β-sheet, 22% β-turn, and 6% α-helix. NMR structural analysis supports this observation and indicates specific sequences of preferred structural populations. Evidence for these is indicated by the presence of d_NN nuclear Overhauser effect (NOE) populations and attenuated or absent d_αN NOEs at short mixing times (0.1 s), ³J_αN coupling constants of 5 and 10 Hz, and chemical shifts significantly removed from random coil positions. The NH₂-terminal VVL sequence primarily exists in an extended chain conformation by virtue of large d_αN NOEs and 9-10 Hz ³J_αN coupling constants. Residues C10-N16 have turn-like or helix character with a run of d_NN and d_βN NOEs and attenuated d_αN NOEs. These midchain reversals include the lysine and asparagine residues proposed to be involved in heparin binding and N-glycosylation, respectively, to laminin peptide F-9.