Basic Info Flashcards
What is the active site of an enzyme?
- region where the enzyme binds to the substrate, forming an enzyme-substrate complex
- it is 3-dimensional, often a cleft or crevice of the surface of the protein
What is an enzyme?
A biological catalyst
They increase the rate of a chemical reaction without being used up
They increase the rate by providing a different path for the reaction by lowering the activation energy
How is the substrate bound to the active site of the enzyme?
By multiple weak interactions
- i.e. Electrostatic interactions, hydrogen bonds, van der Waals forces, hydrophobic interactions
- also in some cases by reversible covalent bonds
What determines substrate specificity of an enzyme?
*the properties and spatial arrangement of had amino acid residues that form the active site.
What are the six main groups enzymes are classified into?
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases or syntheses
What does an oxidoreductase enzyme do and give an example?
- transfers electrons
* example: alcohol dehydrogenase
What does a transferase enzyme do and give an example?
- it transfers functional groups
* example: Hexokinase
What does a hydrolase enzyme do and give an example?
- performs hydrolysis reactions
* example: Trypsin
What do lyases do and give an example?
- add or remove groups to form a double bond
* example: pyruvate de carboxylase
What do isomerases do and give an example?
- they transfer groups within a molecule
* example: Maleate isomerase
What do ligases also called synthases do and give an example?
- bond formation coupled to ATP hydrolysis
* example: pyruvate carboxylase
Give three ways an enzyme lowers the activation energy of a reaction.
- orientation
- physical strain
- chemical change
What is an isozyme?
- different forms of an enzyme that catalyse the same reactions
- but they exhibit different physical or kinetic properties
What is a cofactors?
- small non protein units that are needed for some enzymes to carry out their reactions
- they maybe inorganic ions i.e. Zn2+ or Fe2+, or a complex organic molecule– a coenzyme
What is a prosthetic group?
A metal or coenzyme (tightly bound) covalently attached to the enzyme
What is a holoenzyme?
A catalytically active enzyme together with its coenzyme or metal ion
What is an apoenzyme?
The protein part of the enzyme without its cofactor
What are the two groups cofactors are subdivided into?
Metals
Coenzymes- small organic molecules
