(2R)-2-amino-6-[4-[(2S)-2-amino-2-carboxy-ethyl]-5-[(3S)-3-amino-3-carboxy-propyl]-3-hydroxy-pyridin-1-yl]hexanoate

Deoxypyridinoline is one of two pyridinium cross-links that provide structural stiffness to type I collagen found in bones. It is excreted unmetabolized in urine and is a specific marker of bone resorption and osteoclastic activity.