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What do we need enzymes for?

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Enzymes What do we need enzymes for? A biological reaction in which enzymes are not present would be too slow to sustain life at all. Enzymes are biological catalysts, which they have the ability to speed up the rate of reaction without being permanently changed. (It does this by reducing the activation energy). Enzymes are large molecules that work by reacting with another compound or compounds called the substrate to from a short-lived enzyme-substrate complex. This complex is formed at a particular part of the enzymes, located on the surface, which is known as the active site. The complex breaks down to form the products, but leaving the enzymes totally intact (look at figure 1), which is now available to catalyse another cycle. ...read more.


Unlike the effects of pH are normally reversible, with in limits. Restoring the pH back to normal will usually restore the rate of reaction. Amino acids, from which all proteins are made, contain both acidic and basic groups, and in a polypeptide chain there are many of these acidic and basic groups. The secondary and tertiary structure of the enzyme is maintained by bonds between these groups, and other interactions. A change of pH in the environment of the protein alters the ionic charge of the acidic and basic groups, and causes the shape of the protein to change. This change, and changes induced at the active site, may prevent the substrate molecule from making a very close fit to an active sites and the reaction fails to happen. ...read more.


Heat denaturation really represents an irreversible destruction of the tertiary structure of an enzyme protein, changing its shape, and eventually destroying the active sites. As a result there is an apparent optimum temperature, which is about 37�C. figure 2 shows describes the affects of heat more clearly Substrate concentration is also important in controlling the reaction. A low concentration will result in a rapid reaction while a high concentration will end with a slow reaction this is due to the fact that since there are less enzymes presence than substrate. Some substrate will have to wait while the others are reacting. Enzymes differ from most inorganic catalysts in that they catalyst only one reaction or a small range of reactions, while inorganic catalyst isn't highly specific. . ...read more.

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