A purified WzcWT band from an SDS-PAGE gel was excised, dehydrated in 100% acetonitrile for 10 min, and dried in a SpeedVac for 15 min. The sample was then reduced with 10 mM dithiothreitol (DTT) at 56°C for 45 min, followed by alkylation with 40 mM iodoacetamide at room temperature for 45 min in the dark. The gel plugs were subsequently dried using a SpeedVac and digested with trypsin overnight at 37°C for LC-MS/MS analysis.