Purification of NADH: hypothiocyanite oxidoreductase in Streptococcus sanguis.

NADH

hypothiocyanite oxidoreductase (NHOR) activity, found in some oral Streptococci, is postulated to protect these microorganisms against salivary peroxidase-produced hypothiocyanite. NHOR, however, has not been purified so far. The purification of NHOR from crude extracts of Streptococcus sanguis NCTC 7863 strain (by ultrafiltration and anion-exchange chromatography) revealed one fraction of 125 +/- kDa. However, SDS-PAGE electrophoresis provided a single protein of 21.1 +/- 1.2 kDa. This last discovery suggests that NHOR enzyme is a hexameric complex having six subunits.