Solution structure of LC5, the CCR5- derived peptide for HIV-1 inhibition.

The synthetic peptide fragment (LC5: LRCRNEKKRHRAVRLIFTI) inhibits human immunodeficiency virus type 1 (HIV-1) infection of MT-4 cells. In this study, the solution structure of LC5 in SDS micelles was elucidated by using the standard (1)H two-dimensional NMR spectroscopic method along with circular dichroism and fluorescence quenching. The peptide adopts a helical structure in the C-terminal region (residues 13-16), whereas the N-terminal part remains unstructured. The importance of Phe17 in maintaining the structure of LC5 was demonstrated by replacing Phe17 with Ala, which resulted in the dramatic conformational change of LC5. The solution structure of LC5 elucidated in the present work provides a basis for further study of the mechanism of the inhibition of HIV-1 infection. Copyright (c) 2010 European Peptide Society and John Wiley & Sons, Ltd.