2.4. Assay of
b-galactosidase activity
b-galactosidase activity of the enzyme solution was assayed in
the same manner as
a-galacotosidase except that the substrate
used for this enzyme was O-nitrophenylb-D-galactopyanoside.
In
this assay, the amount of O-nitrophenol formed was determined by
measuring the absorbance at 420 nm (Miller, 1972).