Enzymes Function

Enzymes are special proteins which act to speed up chemical reactions because many chemical reactions required for cells to function normally would not take place at the temperature and pH found in the body (Devlin 128). The protein part of the enzyme without any cofactors or prosthetic groups attached is known as the apoenzyme. Not all enzymes have cofactors or prosthetic groups. Cofactors are small inorganic or organic molecules, which are required for enzymatic activity of the apoenzyme, such as the copper loosely bound to lysine oxidase. Prosthetic groups are groups attached to the protein, such as the heme group in the cytochromes, and are tightly bound to the apoenzyme. Once a cofactor or prosthetic group is added to an apoenzyme it is known as a holoenzyme, and it is now an active enzyme. Enzymes act on substrates, and many of these reactions are reversible, so that the product of one reaction can become the substrate for the reverse reaction.

Enzymes exhibit great specificity and will often only react with one substrate (Devlin 128). The specificity of an enzyme is determined by its substrate binding site, which is determined by a particular arrangement of amino acid side chains on the polypeptide backbone, and the arrangement is only able to bind with a specific substrate. Some enzymes are highly specific, e.g. glucokinase only reacts with glucose, whereas others have a broader range of specificity like hexokinase, which can phosphorylate glucose, mannose,

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Category: Medical - E