title: A double staining method for differentiating between two classes of mycobacterial catalase in polyacrylamide electrophoresis gels.
abstract: Mycobacteria produce two classes of catalase, designated T and M. Only the T-catalase also has a peroxidase-like function. When a 3,3'-diaminobenzidine (DAB) peroxidase stain was applied to polyacrylamide gel electrophoresis gels, followed by a ferricyanide negative stain for catalase, isoenzymes of T-catalase appeared as dark bands within a zone of clearing in the green background; the M-catalase appeared only as a clear zone. Heated and unheated preparations could be used to demonstrate the presence of comigrating bands of M and T. The application of the ferricyanide stain after the DAB stain of T-catalase resulted in marked intensification of the positive bands of T-catalase due to nonenzymatic, peroxide-independent reduction of the ferricyanide by the DAB product.
mesh_terms: D002374:Catalase / Q000145:classification / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D005292:Ferricyanides; D009161:Mycobacterium / Q000201:enzymology*; D013194:Staining and Labeling; D004124:p-Dimethylaminoazobenzene
chemical_list: D005292:Ferricyanides; C007931:hexacyanoferrate III; D004124:p-Dimethylaminoazobenzene; D002374:Catalase