OBJECTIVES: The present study was aimed to determine whether trefoil factor 
family (TFF) peptides which were generally considered to be resistant to 
proteolysis could be digested by gingipains, a major proteinases produced by 
Porphyromonas gingivalis.
MATERIALS AND METHODS: Recombinant human TFF1, TFF2, and TFF3 peptides were used 
as substrates. Gingipains including arginine gingipain (RgpB) and lysine 
gingipain (Kgp) were used as enzymes. Trypsin was used as a control protease. 
Matrix-assisted laser desorption/ionization with time-of-flight / time-of-flight 
(MALDI-TOF/TOF) and liquid chromatography mass spectrometry (LC-MS) were used 
for analyzing peptide mass signals and amino acid sequences of digested TFF 
peptides.
RESULTS: MALDI-TOF/TOF analyses demonstrated that Kgp, RgpB, and trypsin were 
able to cleave TFF1 and TFF2 peptides, resulting in different patterns of 
digested fragments. However, impurity in recombinant TFF3 peptide substrates 
affected the interpretations of enzymatic reaction by MALDI-TOF/TOF. LC-MS 
analyses demonstrated that identified fragments of TFF1, TFF2, and TFF3 from 
digestion by gingipains were similar to those by trypsin.
CONCLUSIONS: Using MALDI-TOF/TOF and LC-MS, the present study provides new 
information that gingipains containing trypsin-like activities are able to 
digest TFF peptides.
CLINICAL RELEVANCE: The proteolytic effects of gingipains on TFF peptides may be 
responsible for reduction of salivary TFF peptides in chronic periodontitis 
patients. Further investigations to determine the pathological effects of 
gingipains on TFF peptides in saliva and periodontal tissues of patients with 
chronic periodontitis would be of interest.