KINESIN

Microtubules

Questions

• How much ATP is hydrolysed per step?

• How many rate-limiting steps are there?

• What is the mechanism of movement?

Analyse movement

Simulation of randomness

Michaelis-Menten kinetics

v = kcat [ATP]/(Km + [ATP])

When [ATP] is limmiting: v = [ATP] kcat/Km – linear function

Km: Michaelis constant: concentration of ATP at ½vmax

kcat: Velocity at saturatet [ATP]

Kinesin:Km = 62 +/- 8 µMkcat = 680 +/- 31 nm/s

At limiting [ATP]: kcat/Km = 11 +/- 1 nm s-1 µM-1

Randomness parameter

d = step distancex(t) = position

r = 0: Clock-liker = 1: 1 rate-limiting step0 < r < 1: more ratelimiting stepsr > 1: increasing variance (backwards steps, double steps, biochemically inactivatet states)