... accompanied by increased sensitivity of the enzyme to inhibition by agmatine and putrescine, the decarboxylated deriva-tives of arginine and ornithine, respectively (Fig. 1).However, the most important ... dead-end inhibitor guanidinium chloridewas not substantially altered. Both inhibitions wereslope-linear competitive. As our activity assay is basedon determination of the urea produced by substratehydrolysis, ... active on agmatine[22], the N130D variant of arginase I exhibited nopreferential specificity for arginine over agmatine. Inaddition to supporting a critical role for Asn130 inarginase I, our present...