Analysis of the elastin in the question showed a decreased number of desmosine cross-links. Desmosine is made up of four lysine residues. Therefore abnormal elastin is likely missing lysine necessary for the formation of these desmosine cross-links. Wikipedia article on Desmosine.

Lysine is used in elastin and collagen cross linking; it is cross linked by lysyl oxidase to make collagen fibers