Week 10 Catalysts Enzymes Flashcards
Seven Basic Types of Enzymes
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
Translocases
Oxidoreductases
Catalyse oxidation reduction reactions
Transferases
Transfer functional groups
Hydrolases
Hydrolysis Reaction
Lyases
Removal of functional groups (not hydrolysis)
Isomerases
Catalyse structural reorganisation
Ligases
Molecular coupling driven by ATP (or other pyrophosphate) bonds
Translocases
Assists in moving a molecule across membrane
Enzyme General Properties
- may contain cofactors (Metal ions, nucleotides, heme groups, vitamins etc.)
- Enzyme structure determines function
- Catalytically potent - thousands or millions fold faster
- highly specific for a given reaction
- Have defined pH and Temperature optimums
- Kinetics: More enzyme = faster rate, more substrate = faster rate (Both situations show saturation)
- Enzymes can be inhibited
Enzyme Primary Structure
The sequence of amino acids making the protein
Enzyme Secondary Structure
Alpha helixes, Beta sheets and coils. Motifs are defined by hydrogen bonding patterns.
Enzyme Tertiary Structure
How motifs hold together to form a polypeptide chain. Multiple secondary structure elements come together to form a single-folded polypeptide chain. Changes in direction at the molecular surface can form loops
Enzyme Quaternary Structure
How Polypeptides fit together to form an oligomeric protein. Multiple polypeptide chains assembled to form an oligomeric protein . No covalent interactions.
How do enzymes lower activation energy
Bind and stabilise substrate in the transition state
Fischer Lock & Key
Enzyme fitting into active site like a key in a lock