How to color only the backbone nitrogen atom in PyMOL? - pymol

Question

I have a cartoon representation of a structure. On this structure I want to show the backbone nitrogens colored. I tried
select bb, name n
then tried to color bb by representation and element
But, unfortunately, none of the options seem to give colors. Could you please let me know how to only color the backbone nitrogen?
Thanks

Answer 1

The cartoon representation inside a protein is an average over three atoms in each amino acid: the C alpha and the amide bond's C and N atom. I'm not sure how you imagine it should look if only the "N part" of this representation should be colored.
Be aware: the cartoon's color is determined through the C alpha, so coloring the N will do nothing, however, if you color the C alpha (name CA), you will color the full cartoon.
if you want to have a helix with alternating colors, you should take a look at
spectrum which allows an alternating color of the cartoon. Maybe you could fiddle something together with it.
E.g. a 9mer peptide would have red white and blue alternating on each amino acid like this:
spectrum count, red white blue red white blue red white blue red white blue red white blue red white blue red white blue red white blue red white blue, 9merselection