Enzymes Flashcards
What is the function of beta galactosidase
to hydrolyse lactose (products are galactose and glucose) and other galactosides
Michaelis - menten equation
v = vmax ([s]/km+[s])
What is vmax
the maximal velocity
What is km
the substrate concentration that gives a velocity of half of vmax
Kcat formula
(K2+Kcat)/K1
What is the rate of formation proportional to
the concentration of the enzyme substrate complex
Rate of change[P] formula
Kcat[ES]
Vmax formula
Kcat x [Etot]
What is vmax directly proportional to
the enzyme concentration
V=kcat[Etot] is dependent on what
has linear dependence on enzyme concentration
[S]/(Km+[S]) has dependence on what
hyperbolic dependence on substrate concentration
specifity constant
Kcat/Km
Features of a good enzyme
High Kcat, low Km, Kcat/km is high
What is a lineweaver-burke plot
1/v plotted against 1/[S]
What does the x and y intercept show on a lineweaver-burke plot
X = -1/km. Y = 1/Vmax
Lineweaver-Burke plot equation
1/v = Km/vmax 1/[S] + 1/Vmax
What is the enzyme transition state
highest energy state in a reaction, the binding of a substrate stabilise them and lowers the energy barrier
What is reversible inhibition
competitive inhibition - competing to bind to the active site so the substrate can’t
Velocity with inhibitor equation
V = Vmax ([s]/(km(1+([I]/Ki)) + [S])
What is kmapp formula
km (1+([I]/Ki))
What is Km
the real value for the interaction of the enzyme and substrate
What is km apparent
what it seems to have chnaged during the experiment
What is a good Ki value
low - less inhibitor needed for desired effect
Inhibitors in diagnosis of diseases
Myasthaenia gravis is progressive muscular weakness. The problem is at neuromuscular junction, where the receptors are blocked so acetyl choline can not bind. Condition can be relieved by raising concentration of acetylcholine (increasing acetylcholinesterase)
