Enzyme Kinetics Flashcards
What should I know about enzyme kinetics?
Catalysts
Specific
Control well defined chemical reactions
How de we describe enzyme behaviour?
Substrate concentration [S]
Velocity [V]
Vmax
Maximum velocity of an enzymatic reaction
Km
Km is a substrate concentration and is the amount of substrate it takes for an enzyme to reach Vmax/2
Michaelis-Mentin Model
- K1, K-1, K2
K1 = Forward rate constant
K-1 = Backwards rate constant
K2 = forward rate constant
Km = k-1 + k2/ k1
Michaelis-Menten equation
V = Vmax[S]/ Km + [S]
1/V = Km/Vmax x 1/[S] + 1/Vmax
Linewaever Burk Plot
Enables accurate determination of Vmax and Km
-1/Km = X axis intersection
Vmax = intersection of straight line with y axis
Low Km
Little substrate needed for half-maximal velocity
High Km
Lots of substrate for half-maximal velocity
Glucose Homeostasis and MODY
RBC - Hexokinase = Low Km (maintains energy product even when low conc)
Liver/Pancreas - Glucokinase = High Km (glucose sensing)
Proline Hydroxylases
O2 as substrate to regulate the HIF TF
High Km for O2
Enables O2-sensitive O2 sensing over physiological ranges of PO2
Von Hippel Lindau Syndrome
Reversible Inhibition
Competitive - binds to active site, blocks
Non-Competitive - allosteric inhibition
Irreversible Inhibition
Non-competitive - formation or breakage of covalent bonds in enzyme complex
