Delugeau Lou, Camy Aurèle, Alembik Léna, Poulin Philippe, Gounel Sébastien, Mano Nicolas, Peruch Frédéric, Grelier Stéphane
Laboratoire de Chimie des Polymères Organiques (LCPO), University Bordeaux, CNRS, Bordeaux INP, UMR 5629, F-33600 Pessac, France.
Centre De Recherche Paul Pascal (CRPP), UMR CNRS 5301, University Bordeaux, F-33600 Pessac, France.
Polymers (Basel). 2025 Mar 14;17(6):779. doi: 10.3390/polym17060779.
Enzymatic modification of Kraft lignin under alkaline conditions was investigated using bilirubin oxidase (BOD) in borate buffer (pH 10). Control solubilization without enzyme addition revealed a notable increase in molar mass (up to 1.7-fold) and potential borate complexation with lignin hydroxyl groups, as evidenced by thermogravimetric and B NMR analyses. BOD treatments induced substantial polymerization, with molar mass increases of up to 4-fold for insoluble fractions after 24 h, while soluble fractions exhibited progressive increases over 5 days. Quantitative P NMR showed reductions in aliphatic and phenolic hydroxyl groups by 20%, suggesting oxidative coupling reactions, particularly through 4-O-5' and 5-5' linkages. Solid-state C NMR confirmed structural changes associated with polymerization. Dynamic light scattering (DLS) indicated the presence of colloidal aggregates, potentially explaining challenges in HSQC NMR signal acquisition. These findings highlight the efficacy of bilirubin oxidase in catalyzing lignin polymerization and underscore the structural impact of borate-lignin interactions in alkaline media, paving the way for advanced lignin valorization strategies.
在硼酸盐缓冲液（pH 10）中使用胆红素氧化酶（BOD）研究了碱性条件下硫酸盐木质素的酶促修饰。不添加酶的对照增溶显示摩尔质量显著增加（高达1.7倍）以及硼酸盐与木质素羟基的潜在络合，热重分析和硼核磁共振分析证明了这一点。BOD处理诱导了大量聚合，24小时后不溶性部分的摩尔质量增加高达4倍，而可溶性部分在5天内逐渐增加。定量磷核磁共振显示脂肪族和酚羟基减少了20%，表明发生了氧化偶联反应，特别是通过4-O-5'和5-5'键。固态碳核磁共振证实了与聚合相关的结构变化。动态光散射（DLS）表明存在胶体聚集体，这可能解释了异核单量子相干核磁共振信号采集方面的挑战。这些发现突出了胆红素氧化酶在催化木质素聚合方面的功效，并强调了硼酸盐 - 木质素相互作用在碱性介质中的结构影响，为先进的木质素增值策略铺平了道路。
