Fig. 1.

pH optima of P. gingivalis whole cell sialidase activity and purified recombinant SiaPG. MUNANA was incubated with SiaPG for 1 min or P. gingivalis (ATCC 33277) for 1 h, in a variety of buffers with variable pH. Reactions were halted and the pH equalised by addition of an excess of sodium carbonate-bicarbonate buffer, pH 10.5. Sialidase activity catalysed the production of 4-MU from MU-NANA, which was quantified by measuring fluorescence of the reactions at excitation and emission wavelengths of 350 and 450 nm. (a) SiaPG (b) P. gingivalis . Data shown represent the mean of one experiment where each condition was repeated three times. Error bars, sem.