CLASSIFICATION OF ENZYMES PRESENTED BY SANIA TAHRIM DEPARTMENT

CLASSIFICATION OF ENZYMES PRESENTED BY: SANIA TAHRIM DEPARTMENT OF ZOOLOGY KARIM CITY COLLEGE, JAMSHEDPUR U. G Sem 4 , CC – 10

CLASSIFICATION OF ENZYMES �Enzymes can be classified by two main criteria: either amino acid sequence similarity (and thus evolutionary relationship) or enzymatic activity. �Enzyme activity. An enzyme's name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase. Examples are lactase, alcohol dehydrogenase and DNA polymerase.

CLASSIFICATION OF ENZYMES �Different enzymes that catalyze the same chemical reaction are called isozymes. �he first Enzyme Commission, in its report in 1961, devised a system for classification of enzymes that also serves as a basis for assigning code numbers to them.

CLASSIFICATION OF ENZYMES �These code numbers, prefixed by EC, which are now widely in use, contain four elements separated by points, with the following meaning: �i) the first number shows to which of the six main divisions (classes) the enzyme belongs.

CLASSIFICATION OF ENZYMES �(ii) the second figure indicates the subclass. �(iii) the third figure gives the sub-subclass. �(iv) the fourth figure is the serial number of the enzyme in its sub-subclass.

CLASSIFICATION OF ENZYMES �The subclasses and sub-subclasses are formed according to principles indicated below. �The main divisions and subclasses are: �EC 1, Oxidoreductases: catalyze oxidation/reduction reactions

CLASSIFICATION OF ENZYMES �EC 2, Transferases: transfer a functional group (e. g. a methyl or phosphate group) �EC 3, Hydrolases: catalyze the hydrolysis of various bonds �EC 4, Lyases: cleave various bonds by means other than hydrolysis and oxidation

CLASSIFICATION OF ENZYMES �EC 5, Isomerases: catalyze isomerization changes within a single molecule �EC 6, Ligases: join two molecules with covalent bonds.