Catalyzes a late step in pyrimidine degradation (PubMed:22525402, PubMed:24526388). Converts N-carbamoyl-beta-alanine (3-ureidopropanoate) into beta-alanine, ammonia and carbon dioxide (PubMed:10542323, PubMed:11508704, PubMed:10415095, PubMed:29976570, PubMed:22525402, PubMed:24526388). Likewise, converts N-carbamoyl-beta-aminoisobutyrate (3-ureidoisobutyrate) into beta-aminoisobutyrate, ammonia and carbon dioxide (Probable). 3-(carbamoylamino)propanoate + 2 H(+) + H2O = beta-alanine + CO2 + NH4(+) 3-(carbamoylamino)-2-methylpropanoate + 2 H(+) + H2O = (R)-3-amino-2-methylpropanoate + CO2 + NH4(+) Strongly inhibited by 50 mM Zn(2+). Not inhibited by EDTA. Competitively inhibited by beta-alanine, 5-aminolevulinic acid (ALA), beta-aminoisobutyrate and 4-ureidobutyrate. kcat is 0.47 sec(-1) with N-carbamoyl-beta-alanine as substrate. Optimum pH is 6.5. Amino-acid biosynthesis; beta-alanine biosynthesis. Homodimer, homotetramer, homooctamer; can also form higher homooligomers. Detected in liver (at protein level). The disease is caused by variants affecting the gene represented in this entry. Belongs to the carbon-nitrogen hydrolase superfamily. BUP family. The purified enzyme was shown to contain 0.5 zinc atoms per subunit, and sequence analysis was used to predict the zinc binding site (PubMed:11508704). The crystal structure indicates a lack of bound zinc ions, and shows that the residues that were predicted to bind zinc are too far apart in space to form a zinc binding site (PubMed:29976570).