Enzymes Pt2

Question 1

How do we assess rates of enzyme catalysed reactions?

Answer 1

-Enzyme kinetics
-Quantitative aspects of catalysis
-Rate of substrate conversion into products

Question 2

What is V in enzyme kinetics and how what can affect it?

Answer 2

Number of moles of product formed per second
(Reaction velocity)

And can vary with S (substrate concentration)

Question 3

What is the Michaelis and Menten equation?

Answer 3

V=Vmax [S]/Km+[S]

V=initial reaction velocity
Vmax=Maximium velocity
Km=Conc of S that gives half Vmax
[S]=Initial substrate conc

Question 4

What can you figure out from Vmax/2?

Answer 4

Km

Question 5

Why is Km useful?

Answer 5

Let’s us estimate where along michaelis menten plot an enzyme is functioning in cell

Question 6

What does it mean if the Km is small or big

Answer 6

Small Km is tight binding and big is weak

Question 7

What is Kcat and its equation?

And what ratio shows us effectiveness of an enzyme towards different substrates?

Answer 7

Rate at which substrates are made into products by a single enzyme (max activity)

Kcat=Vmax/[Et]
[Et]= Enzyme concentration

Kcat/Km as the higher it is shows us enzyme works better on the substrate (S-1M-1=units)

Question 8

Using michaelis menten plot, what other plot can be made?

Answer 8

Lineweaver Burke plot which is linear

Question 9

What does hexokinase do?

Answer 9

Catalyses first reaction in glycolytic pathway

Glucose+ATP —> Glucose-6-phosphate+ADP