Covalent binding of the pyridoxal phosphate-dependent lyase--cystathionine-beta-synthase from chicken liver--by CNBr-activated Sepharose 4B and 6B resulted in catalytically active preparations of immobilized enzyme. Immobilized cystathionine-beta-synthase was shown to possess a higher stability as compared to the native enzyme. The maximum of activity of the obtained preparations was revealed at high temperatures (63 degrees), whereas the native enzyme had the temperature optimum at 40 degrees. The pH optimum of the enzyme activity was markedly shifted towards the alkaline region. The substrate specificity of the immobilized enzyme remained essentially unchanged.