Xenopus allantoicase: Molecular cloning, enzymatic activity and developmental expression

Allantoicase is one of the enzymes of the purine degradation pathway and, i nterestingly, it appears to be lost, together with uricase and allantoinase , during mammalian evolution. Only allantoicases from the ascomycetes S. po mbe, S. cerevisiae, and N. crassa have already been cloned, although the ac tivity has been reported also in fishes and amphibians, By screening a cDNA expression library of Xenopus liver, me have cloned a 1491-bp-length cDNA coding for a 389 amino acid protein that shows an high similarity with the enzyme allantoicase. We have found that allantoicase mRNA is abundantly exp ressed in kidney and liver, but at much lower level is also present in brai n, testis, intestine, and lung. We have detected enzymatic activity in crud e extract from kidney, liver, and lung; we have also determined kinetic par ameters (K-m = 8.44 mM, V-max = 6.94 mu mol min(-1) per mg protein) in kidn ey. During embryo development, we have detected allantoicase transcript and activity starting from 1 and 5 days after fertilization, respectively. (C) 2000 Academic Press.