Keratin keeps the coiled-coil structure is hydrophobic interactions between apolar residues along the keratins helical segments. Limited interior space is the reason why the triple helix of the (unrelated) structural protein collagen, found in skin, cartilage and bone, likewise has a high percentage of glycine. The connective tissue protein elastin also has a high percentage of both glycine and alanine. Silk fibroin, considered a β-keratin, can have these two as 75–80% of the total, with 10–15% serine, with the rest having bulky side groups. The chains are antiparallel, with an alternating C → N orientation. A preponderance of amino acids with
Collagen the form of dietary supplement or functional foods and beverages with the intent to aid joint and bone health and enhance skin health. Hydrolyzed collagen has a much smaller molecular weight in comparison to native collagen or gelatin, study suggests that more than 90% of hydrolyzed collagen is digested and available as small peptides in the blood stream within one hour. From the blood, the peptides (containing hydroxyproline) are transported into the target tissues (e.g., skin, bones, and cartilage), where the peptides act as building blocks for local cells and help boost the production of new collagen fibers. Collagen is