The position of the cell penetrating peptide penetratin in SDS micelles determined by NMR.

Penetratin is a 16 residue peptide, RQI KIWFQ NRRMK WKK-amide, with the ability to penetrate cell membranes and a sequence taken from the homeodomain of the Drosophila Antennapedia transcription factor. 600 MHz 1H-nuclear magnetic resonance has been used to study the structure and location of penetratin interacting with a sodium dodecyl sulphate micelle. The positioning of penetratin in the micelle was studied by adding paramagnetic probes (Mn2+ ions, 5-doxyl and 12-doxyl stearic acid) to the solvent. The results show that the peptide is a straight helix positioned with its C-terminus deep inside the micelle and its N-terminus near the surface of the micelle.