Application of a Metal Switch to Aqualysin I, a Subtilisin-type Bacterial Serine Protease, to the S3 Site Residues, Ser102 and Gly131

Abstract

We applied ‘metal switch’ experiments to the S3 site residues, Ser102 and Gly131, of aqualysin I, a subtilisin-type serine protease. We showed that two histidines introduced at these positions did take part in histidine-metal-histidine bridge formation, and metal ions inhibited the protease activities. These results indicate that two histidines are near each other, and both side chains are metal-accessible. This is the first report on application of the metal-switch technique to a subtilisin-related enzyme.

• aqualysin I
• subtilisin
• Thermus aquaticus YT-1
• metal-switch
• S3 site