Arginase (EC 3.5.3.1: L-arginine amidinohydrolase) is a key enzyme of the urea cycle that catalyses the conversion of arginine to ornithine and urea, which is the final cytosolic reaction of urea formation in the mammalian liver. The recombinant strain of the yeast Saccharomyces cerevisiae that is capable of overproducing arginase I (rhARG1) from human liver under the control of the efficient copper-inducible promoter CUP1, was constructed. The (His)(6)-tagged rhARG1 was purified in one step from the cell-free extract of the recombinant strain by metal-affinity chromatography with Ni-NTA agarose. The maximal specific activity of the 40-fold purified enzyme was 1600 mu mol min(-1) mg(-1) protein. (C) 2011 Elsevier Inc. All rights reserved.