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What are enzymes?

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Background Research What are enzymes? Enzymes are biological catalysts. They speed up the chemical reactions which go on inside living things. Without them the reactions would be so slow that life would stop all together. Enzymes are extremely efficient at doing their job. Here is an example. Some of the chemical reactions which take place in our cells, for example in the liver, produce a by-product call hydrogen peroxide. Hydrogen peroxide is very poisonous so it must be got rid off quickly. Under the influence of an enzyme called catalase, the hydrogen peroxide is broken down into harmless water and oxygen. Catalse acts very quickly: one molecule of it can deal with six million molecules of hydrogen peroxide in one minute. ...read more.


Maltose (substrate) Glucose (product) The substance which the enzyme acts on is called the substrate - in this case maltose. The new substance or substances formed as a result of the reaction are the products. In this case there is just one product: glucose. The enzyme catalysing this particular reaction is maltase. This reaction will go in either direction. In other words the reaction is reversible: maltose can be turned into glucose, or glucose into maltose. The enzyme will work either way. If there is a lot of maltose present compared with glucose, the reaction will go from left to right; if there is a lot of glucose present compared with maltose, it will go from right to left. ...read more.


Most intracellular enzymes work best in neutral conditions, i.e. conditions that are neither acidic nor alkaline. How do enzymes work? Molecules are constantly moving about and bumping into each other. Now when a substrate molecule bumps into a molecule of the right enzyme, it fits into a depression on the surface of the enzyme molecule. This depression is called the active site. The reaction then takes place and the molecules of the product leave the active site, freeing it for another substrate molecule. The active site of a particular enzyme has a specific shape into which only one kind of substrate will fit. The substrate fits into the active site rather like a key fits into a lock. This is why enzymes are specific in their action. When an enzyme is denatured no longer fits. A change in the pH has a similar effect. ...read more.

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