碱性果胶酶（EC：4.2.2.2）是一类在碱性条件下，以反式消去作用断开果胶质主链，产生不饱和的寡聚半乳糖醛酸的酶，在纺织工业的麻类脱胶、棉织品精炼等领域内有着广泛的应用。相比于传统的高碱、高温处理手段，使用碱性果胶酶不仅对果胶质有较好的去除作用，对天然纤维素纤维损伤较小，而且可以减少材料消耗和环境负担，为纺织工业开辟了一条绿色清洁之路。
中科院天津工业生物技术研究所结构生物信息学与整合系统生物学课题组针对如何实现果胶裂解酶工业化高产这一关键环节，开展了一系列的工作。本工作使用简并PCR的方法，从环境基因组中挖掘到一条新型果胶裂解酶序列，并在大肠杆菌中实现了表达。通过对其酶学性质的研究和麻类脱胶效果的评估，发现该酶具有很大的实际应用潜力。本工作又进一步使用高细胞密度发酵优化方法，实现了果胶裂解酶在大肠杆菌中的高产，在7L发酵罐上产量可达1816.2 U/mL，远高于同行报道的水平，有利于工业化大生产的应用，提高了我国在重要工业酶的发酵生产和纺织工业清洁化生产等关键技术领域的研究水平。
该研究得到中国科学院“百人计划”及知识创新项目（KSCX2-EW-G-8）和天津市重大科技攻关项目（10ZCKFSY05600）的资助，申请并获得国家授权专利1项（ZL 2012 1 0064448.0）。
最新研究结果发表在 Process Biochemistry 杂志上，天津工业生物所结构生物信息学与整合系统生物学课题组科研助理王辉林和李小曼为论文的共同第一作者。（生物谷Bioon.com）
生物谷推荐的英文摘要
Process Biochemistry doi.org/10.1016/j.procbio.2013.10.001
Characterization and high-level expression of a metagenome-derived alkaline pectate lyase in recombinant Escherichia coli
Huilin Wanga， 1， Xiaoman Lia， 1， Yanhe Maa， b， Jiangning Songa， c
Alkaline pectate lyases (PLs) play an important role in mild and eco-friendly bioscouring pretreatment processes in the textile industry. However， to date， only a few PLs can be applied in industrial-scale production， and many of them exhibit high production cost， low activity， and/or do not meet the treatment requirements. In this study， an alkaline PL gene was cloned from the metagenomic DNA of alkaline environment soils. The gene pelB consisted of 1263 nucleotides and encoded a mature protein (PelB) of 399 amino acids， which was expressed in Escherichia coli. The maximum catalytic activity of the enzyme exhibited a bimodal distribution at pH 8.1 and 9.8 and an optimal temperature of 55 °C. The Km and Vmax values of PelB were 1.78 g/L and 1084.8 μmol/(L min) at 45 °C， respectively. Substrate specificity analysis demonstrated the high cleavage capability of PelB on a broad range of substrates of natural methylated pectin. Based on the degradation products， PelB was considered to be an endo-acting lyase. Using high-cell-density cultivation in 7-L bioreactor， the highest PL activity (1816.2 U/mL) was achieved. Thus， the recombinant PelB， with promising properties for use in bioscouring in the textile pretreatment process， should be a potential enzyme for industrial applications.
