JESSA S. ARIÑO                                    BSE-3BCentral Bicol State University of Agriculture
   Enzymes are most commonly named by    using a system that attempts to provide    information about the function rather...
1.   The suffix –ase identifies a substance as an     enzyme. The suffix –in is still found in the     name of the first e...
3. The identity of the substrate is often noted  in addition to the type of reaction.glucose oxidase- catalyzes oxidation ...
According to the International union Of Biochemistry an enzyme name has two parts:        -First part is the name of the ...
The International Union of Biochemistry and Molecular Biology have developed a nomenclature for enzymes, the EC numbers; e...
Enzymes are classified into six different groups according to the reaction being catalyzed. The nomenclature was determine...
   EC numbers are four digits, for example    a.b.c.d, where “a” is the class, “b” is the    subclass, “c” is the sub-sub...
 EC   1.   Oxidoreductases EC   2.   Transferases EC   3.   Hydrolases EC   4.   Lyases EC   5.   Isomerases EC   6....
   EC 1. Oxidoreductases :catalyze the    transfer of hydrogen or oxygen atoms or    electrons from one substrate to anot...
   EC 2. Transferases – catalyze group transfer    reactions, excluding oxidoreductases (which    transfer hydrogen or ox...
   EC 3. Hydrolases – catalyze hydrolytic    reactions. Includes lipases, esterases,    nitrilases, peptidases/proteases....
MaltaseMaltose             Glucose   Glucose
   EC 4. Lyases – catalyze non-hydrolytic    (covered in EC 3) removal of functional    groups from substrates, often cre...
FumaraseFumarate              L-malate
   EC 5. Isomerases – catalyzes isomerization    reactions, including racemizations and cis-    tran isomerizations.
3-phosphogycerate   2-phosphogycerate
   EC 6. Ligases -- catalyzes the synthesis of    various (mostly C-X) bonds, coupled with    the breakdown of energy-con...
PhosphatePyruvate           Oxaloacetate
a.   Cellulaseb.   L- amino acid oxidasec.   Sucrased.   Maltasee.   Succinate dehydrogenase
Group             Reaction catalyzed                      Typical reaction   Enzyme example(s) with trivial               ...
A. CELLULASE catalyzes the hydrolysis   of celluloseB. L-AMINO ACID OXIDASE catalyses   the oxidation of L-amino acids.C. ...
Namingandclassification
Namingandclassification
Namingandclassification
Namingandclassification
Namingandclassification
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Namingandclassification

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naming and classification of enzyme

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Namingandclassification

  1. 1. JESSA S. ARIÑO BSE-3BCentral Bicol State University of Agriculture
  2. 2.  Enzymes are most commonly named by using a system that attempts to provide information about the function rather than the structure of the enzyme. Type of reaction catalyzed and substrate identity are focal points for the nomenclature. A substrate is the reactant in an enzyme- catalyzed reaction.
  3. 3. 1. The suffix –ase identifies a substance as an enzyme. The suffix –in is still found in the name of the first enzymes studied such as trypsin, chymotrypsin, and pepsin.2. The type of reaction catalyzed by an enzyme is often noted with a prefix. oxidase- catalyzes oxidation reaction hydrolase- catalyzes a hydrolysis reaction
  4. 4. 3. The identity of the substrate is often noted in addition to the type of reaction.glucose oxidase- catalyzes oxidation of glucoselactate dehydrogenase- catalyzes the removal of hydrogen from lactate ion.Infrequently, the substrate but not the reaction type is given:Urease- catalyses the hydrolysis of ureaLactase- catalyses the hydrolysis of lactose
  5. 5. According to the International union Of Biochemistry an enzyme name has two parts: -First part is the name of the substrates for the enzyme. -Second part is the type of reaction catalyzed by the enzyme. This part ends with the suffix “ase”.Example: Lactate dehydrogenase
  6. 6. The International Union of Biochemistry and Molecular Biology have developed a nomenclature for enzymes, the EC numbers; each enzyme is described by a sequence of four numbers preceded by "EC". The first number classifies the enzyme based on its mechanism.
  7. 7. Enzymes are classified into six different groups according to the reaction being catalyzed. The nomenclature was determined by the Enzyme Commission in 1961 (with the latest update having occurred in 1992), hence all enzymes are assigned an “EC” number. The classification does not take into account amino acid sequence (ie, homology), protein structure, or chemical mechanism.
  8. 8.  EC numbers are four digits, for example a.b.c.d, where “a” is the class, “b” is the subclass, “c” is the sub-subclass, and “d” is the sub-sub-subclass. The “b” and “c” digits describe the reaction, while the “d” digit is used to distinguish between different enzymes of the same function based on the actual substrate in the reaction. Example: for Alcohol:NAD+oxidoreductase EC number is 1.1.1.1
  9. 9.  EC 1. Oxidoreductases EC 2. Transferases EC 3. Hydrolases EC 4. Lyases EC 5. Isomerases EC 6. Ligases A list of the subclasses for each class is given below. Additional information on the sub-subclasses and sub- sub-subclasses (ie, full enzyme classification and names) can be found at the referenced web link. From the Web version, http://www.chem.qmul.ac.uk/iubmb/enzyme/index.ht ml
  10. 10.  EC 1. Oxidoreductases :catalyze the transfer of hydrogen or oxygen atoms or electrons from one substrate to another, also called oxidases, dehydrogenases, or reductases. Note that since these are ‘redox’ reactions, an electron donor/acceptor is also required to complete the reaction.
  11. 11.  EC 2. Transferases – catalyze group transfer reactions, excluding oxidoreductases (which transfer hydrogen or oxygen and are EC 1). These are of the general form: A-X + B ↔ BX + A
  12. 12.  EC 3. Hydrolases – catalyze hydrolytic reactions. Includes lipases, esterases, nitrilases, peptidases/proteases. These are of the general form: A-X + H2O ↔ X-OH + HA
  13. 13. MaltaseMaltose Glucose Glucose
  14. 14.  EC 4. Lyases – catalyze non-hydrolytic (covered in EC 3) removal of functional groups from substrates, often creating a double bond in the product; or the reverse reaction, ie, addition of function groups across a double bond. A-B → A=B + X-Y X Y Includes decarboxylases and aldolases in the removal direction, and synthases in the addition direction.
  15. 15. FumaraseFumarate L-malate
  16. 16.  EC 5. Isomerases – catalyzes isomerization reactions, including racemizations and cis- tran isomerizations.
  17. 17. 3-phosphogycerate 2-phosphogycerate
  18. 18.  EC 6. Ligases -- catalyzes the synthesis of various (mostly C-X) bonds, coupled with the breakdown of energy-containing substrates, usually ATP
  19. 19. PhosphatePyruvate Oxaloacetate
  20. 20. a. Cellulaseb. L- amino acid oxidasec. Sucrased. Maltasee. Succinate dehydrogenase
  21. 21. Group Reaction catalyzed Typical reaction Enzyme example(s) with trivial nameEC 1 To catalyze oxidation/reduction AH + B → A + BH Dehydrogenase, oxidaseOxidoreductases reactions; transfer of H and O atoms (reduced) or electrons from one substance to A + O → AO another (oxidized)EC 2 Transfer of a functional group from one AB + C → A + BC Transaminase, kinaseTransferases substance to another. The group may be methyl-, acyl-, amino- or phosphate groupEC 3 Formation of two products from a AB + H2O → AOH Lipase, amylase, peptidaseHydrolases substrate by hydrolysis + BHEC 4 Non-hydrolytic addition or removal of RCOCOOH → DecarboxylaseLyases groups from substrates. C-C, C-N, C-O RCOH + CO2 or or C-S bonds may be cleaved [X-A-B-Y] → [A=B + X-Y]EC 5 Intramolecule rearrangement, AB → BA Isomerase, mutaseIsomerases i.e. isomerization changes within a single moleculeEC 6 Join together two molecules by X + Y+ ATP → XY SynthetaseLigases synthesis of new C-O, C-S, C-N or C- + ADP + Pi C bonds with simultaneous breakdown of ATP
  22. 22. A. CELLULASE catalyzes the hydrolysis of celluloseB. L-AMINO ACID OXIDASE catalyses the oxidation of L-amino acids.C. SUCRASE catalyses the hydrolysis of the disaccharide sucroseD. MALTASE catalyses the hydrolysis of the disaccharide maltoseE. SUCCINATE DEHYDROGENASE catalyzes the removal of hydrogen from succinate ion

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