Abstract
This experiment is to study and measure the enzyme activity of β-galactosidase in the different concentrations of o-Nitrophenylgalactoside (ONPG) using a spectrophotometer. The spectrophotometer was also set at 420nm, a wavelength which is best for recording the absorbance values for the experiment. From the results, 0.9mM ONPG solution has the highest absorbance and 0.1mM ONPG solution has the least. Also, 0.5mM ONPG solution has the highest rate of enzyme activity and it is the most efficient as the enzyme activity of the ONPG solution continues even though the other concentrations of ONPG solution has already stopped the enzymatic reactions as the substrate is already used up.

Introduction
This experiment is to study and …show more content…

The cuvette was then inserted immediately into the spectrophotometer and the change in absorbance was read off as a function of time. 6. The values of absorbance vs. time for each of the different substrate concentrations was plotted.

Results and discussion Time (s) | 0.1mM | 0.5mM | 0.7mM | 0.9mM | 1.0mM | 0 | 0.056 | 0.049 | 0.176 | 0.210 | | 20 | 0.062 | 0.285 | 0.340 | 0.363 | | 40 | 0.063 | 0.332 | 0.450 | 0.475 | 0.549 | 60 | 0.063 | 0.343 | 0.512 | 0.550 | 0.615 | 80 | 0.063 | 0.370 | 0.543 | 0.610 | 0.650 | 100 | 0.063 | 0.378 | 0.554 | 0.652 | 0.665 | 120 | 0.063 | 0.386 | 0.558 | 0.672 | 0.670 | 140 | 0.063 | 0.405 | 0.559 | 0.684 | 0.674 | 160 | | 0.413 | 0.559 | 0.689 | 0.674 | 180 | | 0.416 | 0.559 | 0.692 | 0.674 | 200 | | 0.420 | 0.558 |