Enzymes benefit chemical reactions but allowing them to happen, they are biological catalysts. However and interestingly, they are not necessarily used up. So, enzymes help large molecules separate in the intended fashion or join in the intended fashion. Enzymes are composed of proteins in amino acids - folded into complex shapes. Smaller molecules can fit into the enzymes like a jigsaw: these are called substrate molecules. The product molecule has to separate from the the enzyme thus it becomes free to join up with substrate molecule. This process is repeated. The place on the enzymes where the molecules go into are called the active sight. The shape of the enzyme is important.
In short, enzymes are: a chain of amino acids, thence proteins coded for by a gene. They are catalysts used for protein synthesis, DNA replication, for breaking big things into small things.
This is usually understood through a lock and key diagram as shown below:
Denatured enzymes by pH or temperature
If the shape of the enzyme changes, the substrate molecules can not fit into it. This is referred to as the enzyme becoming denatured usually do to extreme pH levels or high temperatures.
The enzyme has not been killed. They are just proteins - not living things. High temperatures increase the frequency of collisions between enzymes and other molecules thus the rate of reaction has increased. For most enzymes, body temperature is idealistic for them to work appropriately (about 37 degrees). The wrong pH can denature enzymes. Different enzymes work best at different pH levels. For instance, in our stomach the enzymes called pepsin work best at pH 2 (optimal).
As mentioned, when you
increased temperature there will be more
kinetic energy which the molecules have thus meaning more successful collisions hence an increased rate of reaction. On a graph, there would be a bell shape as the peak of the bell represents the optimum temperature.
If the molecules do not 'lock' into the enzyme, they will bounce off. If the temperature of pH is not favoured by the enzyme, its substrate complex does not form for the molecule. The bonds break.
The active site is complimentary shape to the substrate. It is a specific shape. One enzyme has a certain shape that will only fit in the active zone; the substrate will no longer fits in the enzyme if it denatured so the chemical reaction will not occur.
If you gradually increase the pH and decrease slightly from the optimal pH - the rate of the reaction decreases - the rate of reaction does not result to zero completely.
When are enzymes involved in our world?
Enzymes take part in photosynthesis of plants; they join amino acids together to form proteins; they take part in aerobic respiration. Aerobic respiration is not the same as breathing which is important to consider; it is the chemical reaction that releases energy from glucose. Enzymes catalyse the reaction, usually in the cytoplasm of cells, in tiny objects called mitochondria. The energy tends to be used for contracting muscles joined to molecules forming proteins. Enzymes maintain body temperature in many birds and mammals.
Some microorganisms release enzymes into the environment which we can use for several industries to improve standards of living.
Are they in products we use today?
Well, why are they referred to as 'biological'? This is because the detergents contain enzymes that digest proteins and fats in order to make water-soluble products, as this helps to remove stains hence enzymes are biological catalysts.
How does our body stop the denaturing of enzymes?
You might come across a 'buffer', it is a solution that stops the pH from changing so much. We have buffers in our body so the chemical reactions will continue to happen at the optimal level. For instance, in aerobic respiration, the carbon dioxide formed causes carbolic acid. This will lower the pH of blood if you breathe more often. When one breathes more often, more respiration occurs, so more carbon dioxide is released as a product of that reaction hence carbolic acid.
It is so important for the pH to remain constant in our bodies - for our well-being.
