Nitrogen is an essential nutrient in plants including many crops. The storage and remobilization of nitrogen constitutes the main metabolic process for growth and development of plants. Ureide pathway is the lately characterized metabolic route for purine degradation and is conserved in plants, as well as some bacteria and fungi. The catabolic pathway catalyzes in a stepwise manner a conversion of N-rich uric acid into glyoxylate, with the release of ammonia, and plays a pivotal role in the storage and recovery of nitrogen from metabolites. In Next Generation BioGreen21 project, we aim to understand structural and functional features of enzymes involved in this nitrogen recycling pathway, by using genes from Arabidopsis thaliana. In this study, we report our current progress on this project including two different enzymes; ureidoglycine aminohydrolase (UGlyAH), and ureidoglycolate amidohydrolase (UAH). In UGlyAH, the metal-binding site plays a crucial role in catalysis, with a release of ammonia. We were able to characterize catalytic residues in the active site and provides a detailed view of a metal-dependent enzyme mechanism. Recently, we were able to characterize structural properties of UAH. Based on our analysis, we are performing enzymatic analysis to identify functional aspects of the enzyme. Taken together, these studies would provide a novel functional feature of the enzymes involved in the nitrogen recycling pathway and could serve as a framework to develop crops with an enhanced N-efficiency.