B.7. Proteins and Enzymes [HL] Flashcards
Michaelis-Menten Equation
E + S ⇌ ES → E + P
Vmax
Max velocity achieved by the system at the max (saturating) substrate conc.
+ Indicates how fast the enzyme can catalyse the reaction
Km
The substrate concentration at which the reaction velocity is 1/2 of the Vmax
+ Enzymes have varying tendencies to bind to their substrate (affinity)
High Km
High conc. of substrate = needed to saturate the enzyme = low affinity
- Therefore = lower enzyme activity
Low Km
High affinity of the enzymes towards the substrate = lower conc. needed to saturate the enzyme
- Therefore = higher enzyme activity
Km is ___ for a certain enzyme
FIXED
+ regardless of its conc. essentially a measure of the affinity of an enzyme for its substrate and thus its effectiveness
UV-visible spectroscopy
A common technique for the determination of the concentration of the protein by the protein’s ability to absorb light in the UV-visible region.
What are the 2 relationships that UV-Vis spectroscopy of proteins depend on?
1) Proteins need to be made into coloured compound such that the intensity of the colour depends upon the conc. of the protein in soln.
2) Beer-Lambert Law
One way to make proteins into coloured soln.
+ Add dye called Coomassie Brilliant Blue
+ The coloured complex w/ the dye = absorbs light at a part. wavelength. → 595 nm
Beer-Lambert Law eq.
A = log Io/I = Ɛlc
What is Io in the Beer-Lambert Law?
Intensity of the incidence radiation
What is I in the Beer-Lambert Law?
Intensity of the transmitted radiation
What is Ɛ in the Beer-Lambert Law?
Molar absorption coefficient (a constant for each absorbing substance)
What is l (Lower case L) in the Beer-Lambert Law?
Path length of absorbing soln = usually 1.0 cm
What is c in the Beer-Lambert Law?
Concentration
