A Hybrid Photo/Biocatalytic System for the Sustainable Synthesis of L‐Alanine From Urea and Pyruvate

Developing sustainable routes to biodegradable polymers from renewable feedstocks is key to reducing reliance on petroleum and mitigating environmental pollution. Amino acids, such as L-alanine, are valuable monomers for biodegradable nylons. Artificial photosynthesis has recently been applied to amino acid synthesis, yet the use of biomass-derived nitrogen sources such as urea in visible-light driven L-alanine synthesis has not yet been explored. Here, we present a novel artificial photosynthetic system that converts urea and pyruvate, both biomass-derived compounds, into L-alanine under visible light. In this system, a visible light-driven NADH regeneration system consisting of triethanolamine (TEOA), zinc meso-tetra(4-sulfonatophenyl)porphyrin tetrasodium salt (ZnTPPS4-), and pentamethylcyclopentadienyl (Cp*) rhodium 2,2'-bipyridine (bpy) (Cp*Rh(bpy)(H2O)2+) is integrated with urease (URE), hydrolyzes urea into ammonia, and L-alanine dehydrogenase (AlDH), catalyzes the reductive amination of pyruvate. Under irradiation, the system produced 0.85 mM L-alanine after 24 h (85% yield based on pyruvate). This work represents the first exploration of urea-based, visible-light powered enzymatic L-alanine synthesis, offering a sustainable route to biodegradable polymer precursors from renewable nitrogen and carbon sources.