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SIB2004 6
Enzyme Classification & Nomenclature
Question | Answer |
---|---|
How are enzymes named? | Enzymes are often known by commmon names obtained by adding the suffix "ase" to the name of the name of substrate or to the reaction they catalyse. |
What does Amylase catalyse? | Catalyses the hydrolysis of α-amylose. |
What does Urease catalyse? | Catalyses the hydrolysis of urea. |
What does Xanthine oxidase catalyse? | Catalyses the oxidation of xanthine. |
What does Glucose-6-phosphate catalyse? | Catalyses the hydrolysis of phosphate from glucose. |
Who devised a naming and numbering system? | The Enzyme Commission (EC) of the International Union of Biochemistry and Molecular Biology (IUBMB). |
What does IUBMB stand for? | International Union of Biochemistry and Molecular Biology. |
What does EC stand for? | Enzyme Commission. |
How many major classes can enzymes be divided into? | 6. |
What does sub-groups and sub-subgroups do? | Define their functions more precisely. |
What are the classes of enzymes? | Hydrolases Isomerases Ligases Lyases Oxidoreductases Transferases |
What do oxidoreductases catalyse? | Catalyse oxidation-reduction reactions. |
What are examples of oxidoreductases? | Dehydrogenases Oxidases Peroxidases |
What is the formula for oxidoreducatase? | A– + B → A + B- A+ + B → A + B+ AH + B → A + BH |
What do transferases catalyse? | Catalyse transfer of functional group from one molecule to another. |
What are examples of transferases? | Transaminases Transmethylases |
What is the formula for transferase? | A-X + B → A + X-C |
What do hydrolases catalyse? | Catalyse hydrolytic cleavage (hydrolysis reactions). |
What are examples of hydrolases? | Digestive enzymes such as: Sucrase Amylase Maltase Lactase |
What is the formula for hydrolase? | A–B + H2O → A–OH + B–H |
What do lyases catalyse? | Catalyse the removal of a group or addition of a group to a double bond, or other cleavages involving electron rearrangement. |
What is an example of a lyase? | Decarboxylase |
What is the formula for lyase? | XY=A-B → A=B + X-Y |
What do isomerases catalyse? | Catalyses intramolecular rearrangement. |
What are examples of isomerases? | Racemases Cis-trans isomerases |
What is the formula for isomerases? | XY=A-B → YX=A-B |
What do ligases catalyse? | Catalyse reactions in which two molecules are joined. |
What is an example of a ligase? | DNA ligase |
What is the formula for ligases? | A + B → A-B |
How many parts (numbers) has the EC of the IUBMB given to each enzyme? | 4 |
What do the first three numbers of an enzyme indicate? | Major Class Sub Class Sub-sub Class |
What is the last number of an enzyme and what does it indicate? | A serial number, indicating the order in which each enzume is added to the list, which is continually growing. |
Example of EC Numbers on Triose phosphate isomerase is listed as EC 5.3.1.1. | It's an isomerase d and in the third 3 subclass. It is in the first 1 sub-subclass (those that interconvert aldoses and ketoses) and is the first 1 entry (of 19 so far) in this sub-subclass. |