Question

Problem Three An equilibrium dialysis experiment was performed to characterize the binding affinity of a mouse IgG or human IgG antibody for an antigen, GAD65. The association constant for the monoclonal mouse IgG is 4.75 x 10' M and for a human IgG is 1.3 x 100m ! a. Calculate the dissociation constant for each antibody. Which antibody has a higher binding affinity for GAD65? Explain. b. For a GAD65 concentration of 0.7 nM, calculate the fraction of free Ab sites for each antibody. Initial State Final State Ab-Ag Ab Ag Ab Ab Varying Amounts of Antigen Ab-Ag Ab Ag Ag Ag-Ab-Ag Ab-Ag Ag Ab Ag Membrane permeable to Ag only

Answer 1

Griven, Association constant of a Mouse Ig a = 4.15x 108M' Humon Ig Gi = 1.3x100 ml Dissociation constant of mouse agar a) Association constant 4*45*108M" Mouse Ig G = 0.21 x 10 Dissociation constant of M Humen Igor. Ass constant 1.3 * 10'0m) - I Humon IgG = 0.76x100M → Dissouation constant of Humon 1961 < mouse Igcu. smaller the dissociation constant, higher the offinity i Affinity of Humon IgG is higher If cm моих. Те си от СУ А) 65.

GAD65 concentration 0.7 mm = 0.7 x 109 m. Fraction for mouse ag Gr. - (0.21 x 10-8 bu) x 0.7 x 10-9m (0.21x10-8M] [0-46x10tom] - 9.2 o Praction for Human IgG & persones (0.76x10 com) x 0.7x10 "M [0.21x108 m3 (0.16*10-10 m]