Immobilized Enzymes (Yeast)

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Immobilized Enzymes (Yeast)


Catalase is an enzyme found in living cells and is used to break down

peroxides. Yeast cells, which contain catalase, are used to catalyse

the decomposition of hydrogen peroxide solution into water and oxygen

gas. The yeast cells were immobilized in sodium alginate beads in this

experiment. Immobilized enzymes are widely used in biotechnology

processes. They can be reused and is more stable at extremes of

temperature and pH, thus improves the economy of the process. It is

specifically easier in controlling the amount of enzymes in this

experiment. The rate of reaction on excess hydrogen peroxide solution

was investigated under different yeast concentrations: 15, 20, 25, 30,

35, 40, 45, 50, 55, 60, 65, 70, 75 and 80 beads. The experiment was

carried out in a water bath to ensure constant in temperature, and

oxygen gas produced was collected under an inverted water-filled

burette through a delivery tube. The volume of gases collected was

recorded after 3, 5, 7 and 9 minutes. Factors that would affect the

results were kept constant, such as temperature, pH level and

humidity. The results obtained were satisfying. The larger number of

beads used, the more gases collected. The graph of rate of reaction

against enzyme concentration was plotted and its best fit appeared to

be a straight line, which means the rate of reaction, was directly

proportional to the enzyme concentration. However the major problem

raised in this experiment was that bubbles were formed on the surface

of the beads. Instead of coming off completely, some of them remained

on the bead that the bead could float on the substrate surface. This

showed that the immobilized yeast were not as efficient as we thought.

Catalase enzyme should be used instead of immobilizing the whole yeast

cells that the precision and reliability of the results were seriously



This investigation is carried out by producing immobilized yeast and

to investigate the rate of reaction on hydrogen peroxide solution

under different concentration of enzyme.

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