In this experiment we determined the Michaelis constant known as Km value that reflects the affinity of an enzyme for its substrate. A low value of Km indicates a high affinity of the enzyme for its substrate since maximum velocities will be attained at low substrate concentration. To determine the Km value we obtained the initial rates of enzyme-substrate interaction with double beam spectrophotometer. After that we used three types of plots that is based on the formula V = (Vmax x [S]) / ([S] + Km). These graphs were Michaelis-Menten, Lineweaver-Burk and Eadie-Hofstee plots. Since all of them are used for determination of Km value the results are slightly differs from each other. In our experiment Km values obtained from Michaelis-Menten, Lineweaver-Burk plots are said to be close to each other but the Km value obtained from Eadie-Hofstee plot is obviously different from the others. When we compare the R2 shows a huge difference compared to other plots and far from R2 value of 1. That’s why the Km value obtained from Eadie-Hofstee plot is unreliable. constants, which measures how well the data line up, Eadie-Hofstee plot

…