background [0,0,0] set ambient 40 set specular on set specpower 8 select all wireframe off select protein set hetero off ribbons color group select nucleic trace 10 color cpk cpk 80 wireframe 40 select hetero & !water cpk 80 wireframe 40 color cpk select *.Fe? cpk color cpk select Ca cpk color cpk select *.Mg? cpk color cpk select *.Zn? cpk color cpk select *.Cu? cpk color cpk select *.Ni? cpk color cpk select *.S? & !protein cpk color cpk center protein, nucleic select *