SECONDARY STRUCTURE OF AN ANTIBACTERIAL PEPTIDE ABP3 STUDIED BY 2-DIMENSIONAL PROTON-NMR

An antibacterial peptide Abp3, an analogue of cecropin B, was investig ated by two-dimensional proton-NMR at pH 5.0 in aqueous solution with 15% (v/v) hexafluoroisopropanol. The peptide, which consists of 35 ami no acids, was synthesized chemically. Most resonances of the main-chai n and side-chain protons were assigned. Several medium range NOE conne ctivities were observed, showing two separate alpha-helices with one a mphiphilic in N-terminal domain (residues 5-21) and the other hydropho bic in C-terminal domain (residues 25-35) and a hinge region between t hem. The J coupling constants and the chemical shifts in these section s also supported the conclusion. (C) 1998 Elsevier Science B.V. All ri ghts reserved.