open 1quv
delete solvent

# the following command removes the residues from the main surface and puts
# them in a different "surface category" named "loop"
surfcat loop :15-41

# then just show the main surface
surf

ribbon loop
color blue,r
~disp

# can use "loop" in findclash command, with options to select and color 
# the clash atoms (red by default), but not to draw lines (make false)
findclash loop overlap 0.01 select true color true make false

# promote selected atoms to whole residues for display
sel up
disp sel
~sel
preset apply pub 1
col byatom loop