Lecture 6-7 - enzyme catalysis

Lecture 6-7 - enzyme catalysis - (Topic5 ....

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Lecture 6 – Enzyme Catalysis (Topic 5)  Enzymes are biological catalysts. They perform nearly all chemical  transformations in cells. They accelerate a reaction, but are unchanged by it.  More enzymes are proteins. The protein name ends with “ase” if it is a catalyst.  Although they are proteins, it also consists of some RNA.  Enzymes are often very specific. Only act on one of a few substrates (substrate is  the molecule on which an enzyme acts) Enzymes carry out a limited number of chemical reactions. They do not affect the  basic drive (thermodynamics) of the reaction, but they enhance the speed behind  the transformation.  Enzymes can carry out the following chemical reactions: o Hydrolytic (cleavage using water) o Condensation (connecting molecules together) o Isomerization (rearrange bonds) o Redox (gain or loss of electrons)  o Group transfers (transfer chemical group)  The active site of the enzyme is part of the enzyme where the reaction takes place  it is a small part of the enzyme surface (5% or less). It is often a cleft of crevice  between domains.  The substrate binds to the active site. There are multiple weak bonds that are  associated with keeping the enzyme and substrate together and once the reaction  occurs, the substrate dissociates from the enzyme Enzymes lower the activation energy for the reaction by creating a favourable  environment for the transition state. The activation energy is the energy 
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This note was uploaded on 02/09/2012 for the course SCIENCE 2820 taught by Professor Brandl during the Spring '11 term at UWO.

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Lecture 6-7 - enzyme catalysis - (Topic5 ....

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