Yechiel Shai is a Professor of Biochemistry and Biophysics at the Department of Biological Chemistry at the Weizmann Institute of Science. He received a BSc. in Chemistry in 1977 from Bar-Ilan University, MSc in Organic Chemistry in 1979 and Ph.D. in Peptide Chemistry in 1985 both from the Weizmann Institute of Science. He then carried out postdoctoral research on molecular recognition at the National Institute of Science, Bethesda until 1988, when he took a position as an investigator at the Department of Membrane Research at the Weizmann Institute of Science. He was promoted to Associate Professor on 1995 and to full Professor on 2002. Yechiel Shai is studying peptide/protein-membrane interactions and protein-protein recognition within the membrane milieu. More specifically, he is studying membrane active innate immunity host defense antimicrobial and antifungal peptides and lipopeptides. Since 1991 he has established the "carpet" mechanism as an efficient membrane destruction process used by many AMPs and lipopeptides, and studies parameter controlling the cell specificity of AMPs. In the field of virus-host interaction he is investigating how gp41, the envelop protein of HIV1 catalyzes virus-cell fusion. He also studies new mechanisms by which HIV can evade the immune response. In addition, as part of studying general aspects of protein-protein recognition within the membrane milieu, he discovered that peptides with opposite chiralities can specifically assemble in the membrane, in contrast to the well accepted dogma on recognition outside the membrane milieu. These findings allow to develop new D,L-amino acid containing peptides that serve as novel inhibitors of membrane proteins.