Bovine carboxypeptidase A (peptidyl-L-amino-acid hydrolase, EC 3.4.17.1) was covalently attached to polyacrylamide beads and to silica-based supports, and also adsorbed on polyethylene terephthalate. The highest immobilized activity (125 U g(-1) solid) was achieved when a polyacrylamide bead support (Akrilex C) possessing carboxylic functional groups activated by a water-soluble carbodiimide was used. The catalytic properties and stability of Akrilex C-carboxypeptidase A were studied and compared with the corresponding properties of the soluble enzyme. The optimum pH for the catalytic activity of the immobilized carboxypeptidase A was practically identical to that for the soluble enzyme (pH 7.5-8.0). The apparent optimum temperature of the immobilized carboxypeptidase A was about 20 degrees C higher than that of the soluble enzyme. With hippuryl-L-phenylalanine as substrate, K-m app for the immobilized enzyme (1.65 mM) was somewhat higher than K-m for the soluble enzyme (1.07 mM). The conformational stability of the enzyme was markedly enhanced by the strongly hydrophilic microenvironment. The immobilized carboxypeptidase A was used for the C-terminal amino acid analysis of peptides.