Conformational behavior of temporin A and temporin L in aqueous solution: A computational/experimental study

M. D'Abramo ¹, A. C. Rinaldi ², A. Bozzi ³, A. Amadei ⁴, G. Mignogna ⁵, A. Di Nola ¹, M. Aschi ^{6 *}

¹Dipartimento di Chimica, Università di Roma La Sapienza, Roma, Italia
²Dipartimento di Scienze e Tecnologie Biomediche, Sezione di Chimica Biologica e Biotecnologie Biochimiche, Università di Cagliari, Monserrato, Italia
³Dipartimento di Scienze e Tecnologie Biomediche, Università de L'Aquila, L'Aquila, Italia
⁴Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma, Tor Vergata, Roma, Italia
⁵Dipartimento di Scienze Biochimiche A. Rossi Fanelli and CNR, Università La Sapienza, Roma, Italia
⁶Dipartimento di Chimica, Ingegneria Chimica e Materiali, Università de L'Aquila, L'Aquila, Italia

email: M. Aschi (aschi@caspur.it)

Keywords

temporins • antimicrobial peptides • molecular dynamics • free energy landscape • circular dichroism

Abstract

Molecular dynamics (MD) simulations and circular dichroism (CD) experiments were carried out on aqueous temporin A and L, two short peptides belonging to an interesting class of natural substances known to be active mainly against Gram-positive/negative bacteria and fungi. Experimental results indicate the higher propensity of temporin L, with respect to temporin A, in forming -helical structures. These results were revisited by long-timescale MD simulations, in which their -helical propensity was investigated in the absence of trifluoroethanol. Results clearly show the higher stability of -helix conformations in temporin L; moreover, an interestingly strong mechanical analogy emerges since both temporins show the same residue interval (from 7 to 10) as the most energetically accessible for -helix formation. Such studies provide some intriguing structural and mechanical evidence that may help in better understanding and rationalizing the conformational behaviour of temporins in water solution and, ultimately, the inner principles of their microbial targets selectivity and mechanism of action at the level of cell membranes. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 215-224, 2006