Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science and Technology, National Engineering Laboratory for Industrial Enzymes, Tianjin 300457, PR China.
Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, PR China.
Int J Biol Macromol. 2020 Mar 15;147:1309-1317. doi: 10.1016/j.ijbiomac.2019.10.095. Epub 2019 Nov 18.
Marine macroalgae have gained considerable attention as renewable biomass sources. Ulvan is a water-soluble anionic polysaccharide, and its depolymerization into fermentable monosaccharides has great potential for the production of bioethanol or high-value food additives. Ulvan lyase from Alteromonas sp. (AsPL) utilizes a β-elimination mechanism to cleave the glycosidic bond between rhamnose 3-sulfate and glucuronic acid, forming an unsaturated uronic acid at the non-reducing end. AsPL was active in the temperature range of 30-50 °C and pH values ranging from 7.5 to 9.5. Furthermore, AsPL was found to be halophilic, showing high activity and stability in the presence of up to 2.5 M NaCl. The apparent K and k values of AsPL are 3.19 ± 0.37 mg mL and 4.19 ± 0.21 s, respectively. Crystal structure analysis revealed that AsPL adopts a β-propeller fold with four anti-parallel β-strands in each of the seven propeller blades. The acid residues at the protein surface and two Ca coordination sites contribute to its salt tolerance. The research on ulvan lyase has potential commercial value in the utilization of algal resources for biofuel production to relieve the environmental burden of petrochemicals.
海洋大型藻类作为可再生生物质资源受到了广泛关注。岩藻聚糖是一种水溶性阴离子多糖，其解聚为可发酵单糖在生产生物乙醇或高附加值食品添加剂方面具有巨大潜力。来自交替单胞菌（Alteromonas sp.）的岩藻聚糖裂解酶（AsPL）利用 β-消除机制切割鼠李糖 3-硫酸盐和葡萄糖醛酸之间的糖苷键，在非还原端形成不饱和的糖醛酸。AsPL 在 30-50°C 的温度范围和 7.5-9.5 的 pH 值范围内具有活性。此外，AsPL 被发现是嗜盐的，在高达 2.5 M NaCl 的存在下表现出高活性和稳定性。AsPL 的表观 K 和 k 值分别为 3.19±0.37 mg mL 和 4.19±0.21 s。晶体结构分析表明，AsPL 采用β-三叶螺旋桨折叠结构，每个三叶桨叶片中有四条反平行的β-链。蛋白质表面的酸性残基和两个 Ca 配位位点有助于其耐盐性。岩藻聚糖裂解酶的研究在利用藻类资源生产生物燃料以减轻石化环境负担方面具有潜在的商业价值。
