Fourth-day Experiments

1 Effect of guanidine chloride concentration on / -galactosidase activity 

In the following experiment, we will study /3-galactosidase denaturation by guanidine chloride following OD of PNP at 405 nm. Enzyme denaturation induces a loss in its activity, which will be observed by the decrease in the OD. 

Students should be given a solution of 6 M guanidine. Then, they should prepare the following guanidine chloride stocks 0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 

Derive the mathematical equation that allows you to calculate the equilibrium constant Keq at each guanidine concentration and plot FQ,q = / ([guanidine]. Finally, determine AG° at each guanidine concentration and plot AG0/ = / ([guanidine] and AG0 = f ([Keq]). Calculate from the last graph the value of Keq. 

Do you obtain the same information from both experiments, at 25 and 37°C  

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