POLYAMINES ENHANCE CALCIUM PYROPHOSPHATE DIHYDRATE CRYSTAL DISSOLUTION

Objective. Alkaline phosphatase (ALP), an enzyme with pyrophosphatase (PP(i)ase) activity, can dissolve calcium pyrophosphate dihydrate (CPPD) crystals. We investigated the CPPD crystal dissolution activity of polyamines, substrates known to enhance PP(i)ase activity. Methods. An in vitro model system for crystal enzyme interaction was used to assess CPPD crystal dissolution both biochemically and morphologically. Results. We demonstrated biochemically and morphologically that polyamines such as spermine and spermidine can enhance CPPD crystal dissolution activity of ALP. Polyamines enhanced ALP induced CPPD crystal dissolution and ALP PP(i)ase activity differentially. By scanning electron microscopy, we observed that polyamines enhanced dissolution stereoselectively at the small end faces (optical 010 faces) of CPPD crystals, indicated by the presence of etch pits. Conclusion. Polyamines assist ALP to promote the stereoselective dissolution of CPPD crystals. In addition to implications for CPPD crystal dissolution, as ALP is present intracellularly, these studies suggest that polyamines and ALP have synergistic effects when ALP PP(i)ase activity is required for intracellular energy metabolism.