Immobilised enzymes are enzymes bounded immovably to a surface and not allowed to dissolve in a solution. Also looking at my graph there is a pattern, this is that as the carbon dioxide increases with time the rate of reaction increases for the beads. The beads are immobilised enzymes.
The rate of reaction increases because the enzyme (immobilised enzymes) and the substrate (glucose solution) have kinetic energy to move. The more energy they have the more number of collisions. Therefore there is a greater chance of the substrate binding into the active site of the enzyme. This produces an enzyme – substrate complex, this then breaks down to give carbon dioxide and alcohol.
Immobilised enzymes have slower rate of reaction than non- immobilised enzymes (free enzymes). This is shown on the graph at 10 minutes. The yeast has a gradient of 0.45 and the beads have a gradient of 0.14.
This is because alcohol is produced from fermentation. Ethanol is the alcohol produced, which eventually accumulates and kills the yeast. The substrate (glucose solution) binds into the active site of the enzyme forming an enzyme-substrate complex. The enzyme-substrate complex breaks down to give the product carbon dioxide and alcohol. The alcohol is the end product inhibitor of a metabolic pathway, which begins to accumulate. The alcohol acts as a non-competitive inhibitor and binds with the enzyme at a site other than the active site. This changes the shape of the structure of the active site. Therefore the rate of reaction decreases.
As the carbon dioxide concentration builds up in the beads the beads will start to rise to the surface, this is because carbon dioxide is denser than water. But if the production of alcohol is slowed down due to the change of structure of the enzyme the beads will not rise because the production of carbon dioxide will also be lowered.
The rate of reaction is also faster for the free yeast because there is a larger surface area for the enzymes to take in the sucrose solution. The higher concentration of substrate (sucrose solution) the higher the chance of the substrate colliding with the active site, which is able to form enzyme-substrate complex. Therefor the rate of reaction increases.
The immobilised enzymes have a smaller surface area so there is a less chance of the substrate binding with the active site. This produces less enzyme-substrate complex; therefor the rate of reaction is lower.
As you can see from my graph both of the curves do not finish at the same place, if I carried on with my experiment eventually the curves would finish at the same place. This is because at T14 for the yeast (value: 14.7) and beads (Value: 12.1) there is a high concentration of substrate, this produces lots enzyme-substrate complex, so the rate of reaction increases. Eventually there will be less substrates then enzymes because more products have been formed. When there are no substrates, there are no enzyme-substrate complex so the rate of reaction is zero.
