Improving Visible Light-driven L-Alanine Production from Biobased Materials Using Water-soluble Zinc Porphyrin and Dual-biocatalysts

Le résumé fourni par la source

Poly(L-alanine) is expected to be a biodegradable nylon because its structure is similar to that of poly(L-lactic acid) (biodegradable polyester). Alanine is industrially produced via the condensation of acetaldehyde with ammonia and hydrogen cyanide to form alanine nitrile. This method requires the use of petroleum resources and highly toxic hydrogen cyanide, and also produces a mixture of L- and D-alanine. Thus, L-alanine with high optical purity production from renewable precursors is very desirable, such as biobased compounds with external renewable energy such as solar light. In this study, visible light-driven L-alanine production from biobased pyruvate and urea with nicotinamide adenine dinucleotide (NADH) regeneration of triethanolamine (TEOA) as an electron donor, water-soluble anionic zinc porphyrin, zinc meso-tetra(4-sulfonatophenyl)porphyrin (ZnTPPS4−) as a visible-light sensitizer and pentamethylcyclopentadienyl (Cp*) and 2,2’-bipyridyl (bpy) coordinated Rh complex ([Cp*Rh(bpy)(H2O)]2+) as a catalyst for selective NAD+ hydrogenation, and dual-biocatalysts consisting of urease (URE; EC 3.5.1.5) from jack beans and L-alanine dehydrogenase from Bacillus subtilis (AlDH; EC 1.4.1.1) was developed. In this system, NH3 production based on the hydrolysis of urea by URE is an important factor for improving the subsequent L-alanine production efficiency. Since it was revealed that [Cp*Rh(bpy)(H2O)]2+ inhibits the enzyme activity of URE, the optimization of the [Cp*Rh(bpy)(H2O)]2+ concentration was investigated. It was also found that a [Cp*Rh(bpy)(H2O)]2+ concentration of 1.0 μM had little inhibitory effect on the enzyme activity of URE. Furthermore, applying the optimal [Cp*Rh(bpy)(H2O)]2+ concentration to the visible light-driven L-alanine production system, stable L-alanine production during the irradiation time was achieved, and the yield of L-alanine from pyruvate was improved up to approximately 25 % after 5 h of irradiation.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.