LL-37 is an antimicrobial peptide that plays a major role in periodontal health. Porphyromonas gingivalis is known to resist host immunity by degradation. Previous work in our lab demonstrated the existence of a salivary component that protects the LL-37 from degradation by proteases of P. gingivalis.
Objectives: Our goals in this study are to purify, identify and characterize this component which we refer to as protectorin.
Methods: One LL-37 protection unit was defined as protection of 500 ng LL-37 /ml incubated for 5 hours at 37°C with P. gingivalis supernatant containing 0.5 units/ml of Arg-gingipains proteases. Purification of protectorin is performed using ammonium sulfate fractionation and affinity purification.
Results: One ml saliva was found to contain 333 protection units. Protectorin activity was detected in an ammonium sulfate fraction containing 60-80% ammonium sulfate.
Affinity purification of salivary protectorin yielded a high molecular weight protein which is now subjected to mass spectrograph analysis.
Conclusions: Our results support our initial hypothesis that salivary protectorin is a high molecular glycoprotein.
This work was supported by the Israel Science Foundation grant number 517/06