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Biotinylated b-galactosidase is prepared from an enzyme of exceptionally high specific activity isolated from a special strain of E. coli. Unlike mammalian b-galactosidase, the activity of this E. coli enzyme is optimal at an alkaline pH, enabling it to be used free of interference from endogenous enzyme activity. For many applications, Avidin D followed by biotinylated b-galactosidase affords a highly sensitive system which can be used in a variety of enzyme immunoassays, including screening for monoclonal antibodies.
One unit is 1 µmole o-nitrophenyl-b-D-galacto-pyranoside hydrolyzed per min. at 37 °C, pH 7.3. |