Effect of a protease derived from the oral bacterium Bacteroides loescheii on the inhibition of calcium-phosphate precipitation by human parotid saliva.

A protease from the culture fluid of this microorganism was purified and characterized using DEAE-Sephadex and chromatofocusing and classified as a thiol protease with a mol. wt estimated as 27,500. It abolished the inhibitory activity of parotid saliva on the precipitation of calcium phosphate from supersaturated solutions. Such proteases may contribute to dental calculus formation.