Enzymes 1 Flashcards
What is an enzyme?
- A globular protein
2. which acts as a biological catalyst
Describe the functions of enzymes
- Catalyse metabolic reactions
- Show great reaction specificity
- Work in mild temperature/pH ranges
- Can be regulated
What is a ribozyme?
A catalytic molecule comprised of RNA
Define a ‘cofactor’
A non-protein component needed for enzyme activity
Define a ‘coenzyme’
A complex organic molecule, usually produced from a vitamin
Define a ‘prosthetic group’
A cofactor covalently bound to/ tightly associated with an enzyme
Define an ‘apoenzyme’
The protein component to an enzyme that contains a cofactor
Define a ‘holoenzyme’
The whole enzyme - apoenzyme and any cofactor
Define ‘substrate’
Molecule added on by the enzyme
Define ‘active site’
Part of the enzyme in which the substrate binds and is acted upon
The free energy change value of an enzyme reacting with a substrate must be ___________.
Negative
The model which accounts for the hyperbolic curve of the velocity of reaction against substrate concentration is called what?
The Michaelis-Menten Equation
What is happening when Vmax is achieved?
All active sites are being used up
Km is equivalent to what?
The substrate concentration which the initial reaction rate is half of the maximum reaction rate.
Why must we approximate Vmax?
Experimentally, the hyperbolic curve of an enzyme-substrate reaction velocity against substrate concentration only ever tends towards Vmax (sort of like an asymptote)
