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 was N-cyclohexyl-N'-(methyl-2-p-nitrophenyl-2-oxoethyl) aminopropyl carbodiimide methyl bromide, but for practical purposes, N-cyclohexyl-N'-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 degrees C and Kmapp was calculated to be 0.37M L-arginine. Immobilization markedly improved the conformational stability of arginase. At 60 degrees 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.