Properties of Pseudomonas AM1 primary-amine dehydrogenase immobilized on agarose

1. The primary-amine dehydrogenase of Pseudomonas AM1 (primary amine:(acceptor) oxidoreductase (deaminating), EC 1.4.99.-) was purified by an improved method and covalently attached to cyanogen bromide-activated Sepharose 4B. The immobilized enzyme showed very little change in its sensitivity to heat and to inhibition by semicarbazide as compared with the soluble enzyme, but had enhanced stability at 0 degrees C. The pH optimum of the immobilized enzyme remained unchanged at pH 7.4. 2. A new type of spectrophotometric assay is described in which sedimentation of the immobilized enzyme in the cuvette is prevented by increasing the viscosity by the presence of 10% (w/w) polyethylene glycol (M1 20 000). Detailed kinetic analysis using this assay showed only insignificant differences in the Km values for n-butylamine and phenazine methosulphate between the soluble and Agarose-bound enzymes. The results are compared with those for other oxidoreductase enzymes immobilized on Sepharose.