Enzymes Flashcards
What is a disulfide bridge?
A tertiary structure bond between two cysteines
What is an ionic bond in proteins?
A tertiary structure bond between two charged amino acids
What are the components of secondary structure in proteins?
α-helix and β-pleated sheet
What defines the primary structure of a protein?
The order of amino acids in a polypeptide
What is quaternary structure in proteins?
A protein made of several polypeptide chains
What is a peptide bond?
Formed by a condensation reaction between two amino acids
How do enzymes catalyse reactions?
Enzymes are biological catalysts that speed up reactions by reducing activation energy
What is the active site of an enzyme?
- A pocket formed by the R groups of 3-12 amino acids
- Has complementary shape to the substrate
What is enzyme specificity?
Each enzyme only catalyses one specific reaction
Example: Maltase hydrolyses maltose but cannot hydrolyse lactose or sucrose.
What is the Lock and Key Model?
The substrate fits perfectly into the active site - like a key into a lock
What is the Induced Fit Model?
The substrate binding forces the active site into the correct shape for catalysis
How does temperature affect enzyme activity?
- Increased temperature gives substrate molecules more kinetic energy
- More collisions
- More enzyme-substrate complexes formed until the optimum temperature
- Once tempeature is too high the enzyme will denatures
How does pH affect enzyme activity?
- Optimum pH: enzyme-substrate complexes form efficiently
- Acidic or alkaline conditions: enzyme denatures
How does enzyme concentration affect enzyme activity?
Increasing enzyme concentration increases reaction rate as more active sites are available
How does substrate concentration affect enzyme activity?
- Increasing substrate concentration increases reaction rate
- At maximum level the reaction plateaus as all active sites are occupied
