Functional enzymology - Enzymatic classification, genome replication and expression

The notions of biology and biochemistry presented in this article and in the [PHA 1 512][PHA 1 514][PHA 1 516], articles involve many enzymes that are essential to the functioning of living organisms.

The first enzymes studied in this article are those involved in gene replication and expression in various living or cell-free organisms.

As the number of enzymes listed is very large, a classification system has been established. The first part of this article is devoted to explaining and detailing this classification system, developed by the International Union of Biochemistry and Molecular Biology, which lists seven main enzyme families according to the reaction catalyzed and the Enzyme Commission codes (EC codes):

• EC 1: oxidoreductases,

• EC 2: transferases,

• EC 3: hydrolases,

• EC 4: lyases,

• EC 5: isomerases,

• EC 6: ligases,

• EC 7: translocases.

While this classification is useful, at first glance, for listing an enzyme and analyzing catalytically related molecules, it does not allow us to specify its role in the organism's cellular life, nor to characterize the enzymes with which it is directly linked.

The classification can be repeated with details ranging from gene expression to the relationships that the enzyme can create with other molecules [PHA 1 516] , to the cellular localization of the enzyme