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FERMENTS

Ferment (enzyme) is a protein which increases the rate of a chemical reaction (that is, functions as a catalyst). The rate of the reaction can increase to 10¹⁰ times in comparison with the rate of the same reaction without the enzyme.

Enzymes are highly specific in the sense that each of them catalyzes only the reactions, where the molecules of one or several certain types take part. Enzymes bond with their substrates. Every enzyme has an active site. Besides the active center, some of ferments are equipped with a regulatory (allosteric) centre. Substances, which influence catalytical activity of a ferment, interact with this region of the ferment.

While catalyzing a reaction, a ferment draws molecules of its substrates tightly together, so those parts of molecules, which are to react, happen to be close to one another. The substrate changes after joining the ferment. Ferment can, for example, attract electrons, and in consequence of this in some bonds of substrate molecules some tension will appear. This can increase chemical reactivity of the molecules.

All ferments contain a protein backbone. In some ferments it can be the only structural component. Sometimes some additional non-protein components are present. These components can either participate in catalytical activity of the ferment, or not. Covalently bonded hydrocarbonic groups often occur in ferment structure, but they do not play direct part in catalytical activity. They influence stability and solvability of ferments. Other factors which are present in ferment structure, are metal ions (cofactors) and low-molecular organic molecules (coenzymes). They can be bonded through either covalent or non-covalent bonds and contribute both in activity and stability of ferments. Demand for presence of cofactors and coenzymes appears, when a ferment must be effectively used in continuous processes. During these processes coenzymes and cofactors can be separated from the protein backbone of the ferment.

There is a classification of enzymes, which was worked out by the Nomenclature Committee of the International Union of Biochemistry in the year 1984. According to the type of reaction, which they catalyze, ferments are subdivided into 6 families:

1. oxidoreductases, which catalyze oxidation-reduction reactions;
2. transferases, which catalyze transfer of atoms, or groups of atoms, among molecules;
3. hydrolases, which catalyze reaction of hydrolysis;
4. lyases, which take part in elimination reactions, when groups of atoms split of the substrate;
5. isomerases, which catalyze geometrical and structural changes inside one molecule;
6. ligases (synthetases), which catalyze formation of covalent bonds between two molecules.

There are classes inside each of the families, and there are subclasses inside the classes. Every ferment has its unique EC-number (EC is Enzyme Commission). It consists of four figures, divided by dots. The first figure is the number of one of the six families. The second one is the number of a class. The third one is the number of a subclass. And the forth one is the unique number of the ferment in its subclass.

Supplementary information Recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology on the Nomenclature and Classification of Enzymes by the Reactions they Catalyse