I'm an undergrad doing some assaying on b-galactosidase (using
o-nitrophenol-b-galactoside as the substrate) from e.coli and
some funny things are turning up. The thing I don't understand most and
can't seem to find any information on the literature is that when adding
lactose to the assay as an alternate chemical (while still including ONPG
in the asasy,) the rate of formation of coloured product of o-nitrophenol
increases with an increase in the concentration of added lactose. I would
have thought that adding lactose would competitively inhibit the
hydrolysis of ONPG. Is there possibly allostery going on? HELP!! I guess
I don't really know enough about the enzyme itself. Any help would be
much appreciated.
Thanx,
Shad
