reported that in the helical structure of collagen, every
circle of the helix contained 3.3 amino acid residues (n ¼ 3.3) with a
pitch of 0.96 nm, and along the central axis of the helix, the distance
between adjacent amino acid residues was 0.29 nm. The d value
that corresponds to the collagens A3 peak value were 0.29 nm,
indicating the helical structure was preserved in the collagens we
extracted from fish scales and skin. The crystallinity of SCC and SKC
were 15.87% and 15.18%, respectively.