Immobilization,characterization, and laboratory-scale application of bovine liver arginase

Arginase isolated from beef liver was covalently attached to a polyacrylamide bead support bearing carboxylic groups activated by a water-soluble carbodiimide. The most favorable carbodiimide wasN-cyclohexyl-Nt’-(methyl-2-p-nitrophenyl-2-oxoethyl) aminopropyl carbodiimide methyl bromide, but for practical purposes,N-cyclohexyl-Nt’-morpholinoethyl carbodiimide methyl tosylate was used. The optimal conditions for the coupling procedure were determined. The catalytic activity of the immobilized arginase was 290–340 U/g solid or 2.9–3.4 U/mL wet gel. The pH optimum for the catalytic activity was pH 9.5, the apparent temperature maximum was at 60°C and K_mapp was calculated to be 0.37M L-arginine. Immobilization markedly improved the conformational stability of arginase. At 60°C, the pH for maximal stability was found to be 8.0. The immobilized arginase was used for the production of L-ornithine and D-arginine.