A SPR method was established to determine the specific binding constants of CD45-FITC to protein A. The specific binding of CD45-FITC was monitored in real time on the SR7500DC Dual Channel System. The characteristic constants for this reaction they were association rate constant

k

a

dissociation rate constant

k

d

association equilibrium constant

K

a

activation energy

E

a

and enthalpy change △

H

. The results indicated that the optimum reaction conditions were under neutral or alkaline medium

with a slightly higher ionic strength and temperature. This method has the characteristics of being fast

simple operation

high sensitivity and less sample

which can be suitable for the investigation of biomolecular interactions of immunoglobulin IgG with protein A.