Enzymes 1 Flashcards
What is an enzyme?
Globular protein, no defined structure and biological catalyst.
Define a ribozyme.
Catalytic RNA molecules with no protein compounds.
Give one function of RNA.
Can form secondary structures like amino acids forming different shapes.
Define cofactors.
Non-protein components which are necessary for cell function.
Define coenzymes.
Complex organic molecules which are usually produced from a vitamin.
Define prosthetic group.
Cofactor which is covalently bonded and necessary for function of an enzyme.
Define an apoenzyme.
Protein component of an enzyme containing a cofactor.
Define a holoenzyme.
Whole enzyme (cofactor and apoenzyme).
Define substrate.
Molecule acted on by the enzyme.
Define an active site.
Part of the enzyme in which the substrate binds to.
Name 2 things enzymes can’t do.
Move equilibrium.
Make a nonspontaneous reaction spontaneous.
Name 3 things an enzyme can do.
Increase rates of spontaneous reactions
Lower activation energy
Accelerate movement towards equilibrium
Define an energy barrier.
The energy required for a reaction to occur.
The active site is ______ to the substrate.
Complementary.
If the active site and the substrate are exactly complementary, then the enzyme substrate complex is ______ stable.
More
What is the active site actually complementary to?
The transition state (catalysis).
Describe entropy reduction.
Molecules react by bumping into each other and enzymes help this happen more frequently to reduce activation energy.
Describe desolvation.
Weak bonds between the substrate and enzyme replace most or all of the hydrogen bonds between the substrate and aqueous solution to make the breaking of bonds easier.
Describe induced fit.
Conformational changes occur in the enzyme structure when a substrate binds.
What are the 3 ways to analyse an enzyme?
Enzyme kinetics
Mutagenesis
3D structure
Describe the process of measuring enzyme kinetics.
Change of substrate concentration changes the initial rate of reaction. As reaction proceeds, substrate is used up and rate of reaction changes. Initial velocity (Vo) can be measured if initial substrate concentration doesn't change. Vmax occurs because all of the enzyme active sites are saturated with substrates.
What is the M-M equation?
Vo = Vmax [S]
Km + [S]
What is the M-M equation with a low substrate concentration?
Vo = Vmax [S]
Km
What is the M-M equation with a high substrate concentration?
Vo = Vmax
