Measurement of proteases in human subgingival dental plaque by fluorescence polarization

Fluorescence polarization (FP) was examined as a rapid quantitative method to assay the proteases in subgingival plaque. Protease activity was measure d by a decrease in FP at 0.5-min intervals over 5 min: using BODIPY(R)-alph a -casein, a protein substrate. To quantitate activity, the least absolute deviation (LAD) slope for each assay was determined. Protease activity incr eased with the quantity of plaque (r = 0.416, P < 0.001). Of the 208 subgin gival plaque samples, 87 contained detectable protease activity, with a mea n of about 4 <mu>g trypsin equivalents above a general background of 1 mug per site. The mean plaque protease activity of 89 paired samples from 15 in dividuals had decreased by 1.1 mug trypsin equivalents per site when measur ed at 8 months after tooth scaling and root planing (P < 0.01). Most isolat es of Porphyromonas gingivalis, Treponema denticola, Prevotella nigrescens, and Prevotella intermedia implicated in the pathogenesis of adult periodon titis exhibited high activity in the FP assay. The assay is rapid, quantita tive and requires only one-tenth of the plaque sampled using a single pass with a Gracey curette at a single tooth site. (C) 2000 Elsevier Science Ltd . All rights reserved.