background [205,205,180]
color cpk 
select DNA 
cartoons off 
cpk off 
wireframe 55 
define set1 (*.O?') 
define set2 (*.OP?)
define set3 (*.N? and DNA)   
define set4 (*.C?') 
define set5 (*.P and DNA)
select within (3.5,set1) and (*.N,*A.O,*B.O) 
select within (4.5,set4) and (*.S,*A.P,*B.P,*B.C,*A.C) 
select within (3.5,set2) and (*.N,*A.O,*B.O) 
select within (4.5,set5) and (*.S,*A.P,*B.P,*B.C,*A.C)