STANDARDIZATION OF MARKER ASSAYS PYRIDINOLINE DEOXYPYRIDINOLINE/

The hydroxypyridinium collagen crosslinks pyridinoline and deoxypyridi noline (Dpd) are released during the degradation of some mature collag ens. Assays for the peptide forms of these crosslinks in blood and uri ne and for the free and total crosslinks in urine have been developed. Currently there is no internationally accepted reference standard for use in any of these assays. Recently the criteria and strategy for th e preparation of a Dpd standard have been described. Using the UV mola r absorptivity of 5160 L/mol/cm at 294 nm in 0.1 mol/L HCl and purity checked by NMR spectroscopy, mass spectrometry and elemental analysis sufficient quantities of this reference standard will have to be prepa red. Protection from photolysis is essential to ensure stability of th e reference preparation. This reference preparation will be suitable f or calibration of immunoassays for free Dpd and for HPLC assays of fre e and total Dpd. The assays for peptide forms of the crosslinks have u sed standards prepared either by enzymatically digesting collagen or s ynthesis of oligopeptides. The problem of standardization of some of t hese peptide assays may be resolved if a reference preparation of dige sted bone collagen can be produced and appropriately characterised.