Introduction, properties, nomenclature and IUB classification of enzymes.
Introduction:
The International Union of Biochemistry and Molecular Biology (IUBMB) is an organization that deals with biochemistry and molecular biology.
The International Union of Biochemistry and Molecular Biology (IUBMB) was renamed IUBMB in 1991.
Classification of Enzymes and Nomenclature:
Chemical reactions in the body are catalyzed by enzymes.
Neither enzymes are consumed nor permanently altered during reactions.
All enzymes are proteins in nature. (Exception: ribozymes, which catalyze RNA molecules).
Enzyme nomenclature depends on a number of factors, including,
A variety of substrates may be used
Common names
It is also based on its regulations
Source of enzymes
Name of the reaction (and the suffix -ase) that is catalyzed
Type on the reaction that is catalyzed (and then by suffix-ase)
Protease
Transferase
Reductase
Dehydrogenase
Isomerase
Nature of substrate
Hexokinase
Alcohol dehydrogenase
Glucokinase
Xanthine oxidase
Source of enzyme
Gastric lipase
Salivary amylase
Pancreatic lipase
Muscle phosphorylase
Hepatic phosphorylase
Based on its regulation
Pepsin
Hormone specific lipase
Thrombin
Trypsin
Systematic Names of Enzymes
Classification based on IUB – international union of biochemistry
By using specific code numbers and unique names, each enzyme is identified by the type of reaction it catalyzes and the type of substrate it uses.
There are six groups classified for enzymes
Class I: Oxidoreductase
ClassII: Transferases.
Class III: Hydrolases.
Class IV: Lyases.
Class V: Isomerase.
Class VI: Ligases.
Class 1 – oxidoreductase
A reduction compound (hydrogen or electrons) is transferred from one redox system to another by oxidoreductases.
Examples – lactate dehydrogenase, xanthine oxidase, cytochrome oxidase, alcohol dehydrogenase, aldehyde dehydrogenase, oxidase.
Class 2 – Transferases
Catalyzing the transfer of other groups between molecules, the transferases function. Coenzymes are generally needed by oxidoreductases and transferases.
Example – methyltransferase, phosphotransferase, aminotransferase,
Class 3 - hydrolases
Water is used to cleave bonds by the hydrolases.
Example – peptidase, glycosidase, protease, phosphatase
Class 4 - lyases
Lyases catalyze reactions in which chemical bonds are either formed or cleaved (also known as synthases), with double bonds either establishing or fading away. Water is not required for the cleavage of bonds. The C-C, C-O, C-N, and C-S bonds are normally broken by lyases.
Example – glutamate decarboxylase, fumarase, argininosuccinase
Class 5 – isomerase
As the isomerases move groups inside molecules, they do not change the constituents of the substrate.
Example – aldose ketose isomerase, mutase, epimerase
Class 6 - ligases
Ligases (synthetases, class 6) catalyze ligation reactions with energy, which are always accompanied by nucleoside triphosphate hydrolysis.
Example – pyruvate carboxylase, DNA ligase, acetyl Co-A carboxylase
EC number (enzyme commission number)
The enzymes in the Enzyme Catalog are assigned EC numbers (Enzyme Commission numbers).
Each enzyme belongs to one of six main classes.
There are also subclasses and subclasses below.
Commonly Asked Questions:
Write in detail about classification of Enzymes.
Labels: Biochemistry
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