reset select colour grey wireframe off spacefill off ribbon off strand off labels off select protein spacefill select hydrogen spacefill off select sidechain and (8,12,16) colour red select sidechain and (9,13,17) colour blue select ala8.CB label 'residue i' select ala12.CB label 'residue i+4' select ala16.CB label 'residue i+8' select ala9.CB label 'residue i+1' select ala13.CB label 'residue i+5' select ala17.CB label 'residue i+9' rotate y 20 rotate z -20 rotate x 90