kappa-Carrageenan is a non-toxic polymer from seaweeds, which becomes reversibly insoluble upon the addition of K+. Its conjugate with the dye, Cibacron Blue 3GA, was used to purify alcohol dehydrogenase from crude yeast extract by affinity precipitation. Response surface methodology was used to optimize conditions for affinity precipitation of the enzyme with the polymer-dye conjugate. Recovery of 58% of the enzyme activity with 13.6-fold purification was obtained. (C) 2003 Elsevier Inc. All rights reserved.