A synthetic peptide reproducing the mitochondrial targeting motif of AKAP121: A conformational study

The conformational features of a peptide derived by the 10-30 sequence of the mitochondrial domain of AKAP121 [Ac-(1)XKKPLALPGMLALLGWWWFFSRKKX(25)-NH2 (X = beta-Ala)] in water and in a water/triflouroethanol (TFE) mixture at 298 K have been determined by NMR and CD spectroscopy. Backbone clustering analysis of NMR-derived structures led to the identification of a single representative structure in water/TFE. The structure of the peptide consists mainly of an a-helix, whose core is the region 7-23, with a less ordered N-terminal part. These data are confirmed by CD analysis. It is noteworthy that the high hydrophobic Trp(16)-Phe(20) segment, that might also mediate interaction with tubulin, is organized in an a-helical wheel. Our conformational data can be the starting point for the development of highly selective peptides that interfere with the biological function of the Protein Kinase A scaffold protein AKAP121. (