Basic

D-Ala versus L-Ala

trans versus cis Ala-Ala

trans versus cis Ala-Pro

proline

peptide bond

alpha-helix (stick)

alpha-helix (cpk)

alpha-helix (surface)

parallel sheet (stick)

anti-parallel sheet (stick)

beta turn (stick)

A-T base pair

G-C base pair