Insulin secondary structure
In this view
the two polypeptide chains are given different colours (blue for A, red
for B).
The coiling, and the straighter connecting sections which can
be clearly seen here,
are a result of the secondary level of protein structure.
Note the superimposed amino acid residue codes and numbers in the
sequence, as well as the letters
corresponding to the chains. This is effectively the primary
protein structure, from which the other levels are built up.
Some of the details which result in the next levels of protein
structure have been left out.