load=1xbr

cpk off
cartoon
rotate -x 90
rotate -y 90
echo "1xbr all"
pause

restrict dna
center selected
cartoon off
rotate -x 30
rotate -y 30
wireframe 
echo "DNA"
pause

define set1 (*.O3' or *.O4' or *.O5') and dna
select set1
cpk 80
echo "deoxyribose oxygen"
pause

cpk off
define set2 (*.OP1 or *.OP2) and dna
select set2
cpk 80
echo "phosphate oxygen"
pause

cpk off
define set3 *.N? and dna
select set3
cpk 80
echo "nitrogen of nucleobases" 
pause