Control of an affinity purification procedure using a thermal biosensor

Abstract
Lactate dehydrogenase (LDH) was recovered from a solution by affinity binding to an N6‐(6‐aminohexyl)‐AMP‐Sepharose gel. An enzyme thermistor unit was employed to continously measure the activity of the unbound LDH. The enzyme activity signal from the enzyme thermistor was used in a PID controller to regulate the addition of AMP‐Sepharose gel to the LDH solution. In another type of experiment, a desktop computer was utilized to control the addition of the adsorbent. Both systems worked satisfactorily, and enabled a rapid and accurate assessment of correct addition of adsorbent.