Enzymes Definition

Enzymes are biological catalysists. Biological because they are made in living cells by proteins. Catalysts as they speed up the rate of a chemical reaction without being changed. Enzymes are made by Proteins. It is necessary to all living organism as they maintain reaction speed of all metabolic reaction at a rate that can sustain life.

Specificity

Enzymes are specific to one particular substrate as the active site of the enzyme, where the substrate attaches, is a complementary shape to the substrate. It is because the enzyme is a protein and has a specific 3d shape. It is known as the lock and key hypothesis.

When the substrate moves into the enzyme’s active site, they become known as the enzyme-substrate complex. After the reaction occured, product leave the active sit as they no longer fit and the enzyme is free to take up another substrate.

Enzymes & Temperature

• Enzyme work the fastest at their optimum temperature.
• Heating to higher temperature will break the bonds that hold the enzyme together and it will lose its shape — it is known as denaturation, and it is irreversible.
• Substrates cannot fit into the denatured enzymes as the shape of the active site is lost.
• The more energy the molecules have, the faster they move, and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction.
• It means that low temperatures do not denature enzymes, it just make them work slower.

Similar graph shape applies to pH too.

Enzymes & pH

• If the pH is too high or too low, the bonds that holds the amino acid chain together to make up the protein can be destroyed. It will change the shape of the active site, so the substrate can no longer fit into it, reducing the rate of activity.
• Moving too far away from the optimum pH will cause the enzyme to denature.

The highest point on the graph is known as the Optimum Temperature / pH.