C5H9NO3

from The Collaborative International Dictionary of English v.0.48
hydroxyproline \hydroxyproline\ n.
   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.
   [WordNet 1.5 +PJC]
    

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