This document contains questions about protein function and enzyme kinetics calculations. It asks the reader to calculate a dissociation rate constant from given association rate and dissociation constant values. It also asks the reader to calculate the antigen concentration needed for 20% binding based on a given dissociation constant. Regarding enzyme kinetics, it asks the reader to calculate the Michaelis constant using the maximum reaction rate, enzyme concentration, substrate concentration, and known catalytic rate constant.

1. Protein Function:
Question 1. Protein A binds to protein B with an association rate of 8.9 x 103 M-1s-1
and an overall dissociation constant (Kd) of 10 nM. Calculate the dissociation rate κd.
Ka = κa / κd, Kd = 1/Ka, so Kd = κd / κa
10nM = κd / 8.9 x 103M-1s-1
Κd = 8.9 x 10-5s-1
Question 2: An antibody binds to an antigen with a Kd of 5 x 10-8 M. At what
concentration of antigen will θ be 0.2?
Θ = [L] / [L] + Kd
Θ([L] + Kd) = [L]
ΘKd = [L] + Θ[L]
Θ(Kd)/ (1- Θ) = [L]
Solving for [L], [L] = 0.2(5 x 108M)/(1-0.2)) = 0.2(6 x 10-8M) = 1.2 x 10-8M

2. Enzyme Kinetics
Question 1: κcat for enzyme A is 600 s-1. Experimentally, when [E] = 20nM, and
[S] = 40 µM, V0 = 9.6 µMs-1. Calculate Km for this enzyme.
Use Equation V0 = Kcat[Et][S] / Km + [S]
9.6 µMs-1 = (600s-1)(20µM)(40µM) / Km + 40µM
Km + 40 µM = 480 µM2s-1 / 9.6 µMs-1
Km + 40 µM = 50 µM
Km = 10 µM
Question 2 we went over in class.