|MadSci Network: Biochemistry|
Enzymes are the large group of proteins, which can be defined as biocatalysators of various metabolic reactions. In simple words an enzyme "speeds up" the reaction process. Thus, the reactions which normally would require several hours, weeks, or months can be completed within miliseconds. The enzyme is involved in lowering the energy level required for the reaction to be run. There are specific enzymes for each reaction occuring in metabolism of a living organism. We define six major groups of the enzymes depending on the specificity of the reaction catalysed by them: - Oxidoreductases - participating in red-ox reactions - Transferases - participating in tranferring certain groups from one molecule to another - Hydrolases - participating in hydrolytic cleavage of the bond in the molecule - Lyases - participating in splitting the molecule into smaller products - Isomerases - participating in changing the molecule into its isomeric form - Ligases - participating in merging two or more molecules into one. The enzymes are proteins. Often they have a non-protein components (heme, nucleotide derivatives, vitamins, carbohydrates, lipids etc.) which are necessary for their action. These components often form so-called catalytic site directly involved in the reaction catalysis. The catalytic site can be formed also by the fragments of the enzymatic protein itself, or by just several amino acid residues which are constituents of this protein. The other important site in enzyme is substrate site (or substrate pocket) which is responsible for the recognition of the substrate - the molecule to be processed during the reaction. The enzyme action can be regulated (accelerated or inhibited) by other compounds. For this reason there are sites specifically responsible for binding such modulators. The complex enzyme-modulator sligthly changes the conformation (shape) of the enzyme molecule - that implies changes in catalytic enzyme properties also. We can say, that almost all metabolic reactions in our organism are enzymatically "supported".
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