TAMM-HORSFALL GLYCOPROTEIN - ROLE IN INHIBITION AND PROMOTION OF RENAL CALCIUM-OXALATE STONE FORMATION STUDIED WITH FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

Tamm-Horsfall glycoprotein (THP) from healthy probands inhibits the pr ecipitation of calcium oxalate, whereas THP from individuals who repea tedly develop calcium oxalate stones has no effect or even promotes pr ecipitation. Using Fourier-transform infrared spectroscopy, we found a structural differentiation between these functionally different THPs: a decisive difference in sialic acid content. Quantitative analysis f or sialic acid showed the same results. THP from healthy probands had a high sialic acid content (51 +/- 9 g/kg), whereas THP from recurrent stone formers had a decreased sialic acid content (21 +/- 4 g/kg). Th is explains the dual role of THP in the precipitation of calcium oxala te and the formation of renal stones and shows the importance of glyco sylation in the function of this glycoprotein.