A crystalline amino acid (C5H9NO3), a hydroxylated proline, obtained by hydrolysis of gelatin or collagen. Chemically it is 4-hydroxy-L-proline. It is classified as nonessential for growth in rats.

An amino acid that is abundant in collagen.

A collagen constituent. May serve as a surrogate for collagen breakdown when assessing bone turnover.

Important amino acid used in structural proteins like collagen.

a crystalline amino acid obtained from gelatin or collagen

Hydroxyproline is a compound similar in structure to the amino acids and is found only in collagen.

Hydroxyproline is referred to as "Hyp". This protein acts as universal biological glue. The primary amino acid in collagen is L-hydroxyproline, a non-essential amino acid. Hydroxproline plays a major role in the manufacture of collagen, connective tissue, skin, ligaments, tendons, bones and cartilage. Hydroxyproline is also necessary in Vitamin D assimilation and Vitamin D is essential in proper calcium absorption.

Hydroxyproline, or hydroxyproline (C5H9O3N), is an uncommon amino acid, abbreviated as HYP, e.g., in Protein Data Bank. Its IUPAC name is 4-hydroxypyrrolidine-2-carboxylic acid. Hydroxyproline differs from proline by the presence of a hydroxyl (OH) group attached to the C (gamma) atom.