(a) Predicted binding models of Bcl-2 in complex with (a) compound 1; (b) mBim BH3 peptide; (c) designed compounds 2; and (d) 4. Bcl-2 is shown in surface representation where carbon, oxygen, nitrogen and sulfur atoms are colored in gray, red, blue and orange respectively. The carbon and oxygen atoms in compounds 1, 2 and 4 are shown in yellow and red, respectively. The mBim BH3 peptide was shown in a light blue helix. Hydrogen bonds are depicted in dotted lines in cyan. Bim peptide residues are labeled in italic.