these findings confirm the assumption , made earlier on the basis of conformational analysis of ( gly-pro-hyp ) n , ( gly-pro-ala ) n , ( gly-ala-hyp ) n , ( gly-ala-ala ) n , that the collagen triple helix contains stable wound triplets with proline in the second position , while the absence of imino acid in the 2nd position facilitates the unwinding of the triple helix .
C0033382
proline
C0020931
imino acid