1. LEOPR (CNRS UMR 5630), Institut de Chimie Moléculaire de Grenoble FR CNRS 2607, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France, Department of Biotechnology Engineering and National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, P.O. Box 653, 84105 Beer-Sheva, Israel, and LEDSS UMR 5616 & ICMG-FR 2607, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France