Veerakumar Sneeha, Manian Ramesh Pathy
Department of Biotechnology, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore, 632014 India.
3 Biotech. 2018 Oct;8(10):445. doi: 10.1007/s13205-018-1470-1. Epub 2018 Oct 9.
Agarases (agarose 4-glycanohydrolase; EC 3.2.1.81) are class of enzymes that belong to glycoside hydrolase (GH) family capable of hydrolyzing agar. Their classification depends on hydrolysis pattern and product formation. Among all the agarases, β-agarases and the oligosaccharides formed by its action have fascinated quite a lot of industries. Ample of β-agarase genes have been endowed from marine sources such as algae, sea water, and marine sediments, and the expression of these genes into suitable host gives rise to recombinant β-agarases. These recombinant β-agarases have wide range of industrial applications due to its improved catalytic efficiency and stability in tough environments with ease of production on large scale. In this review, we have perused different types of recombinant β-agarases in consort with their molecular, physiochemical, and kinetic properties in detail and the significant features of those agarases are spotlighted. From the literature reviewed after 2010, we have found that the recombinant β-agarases belonged to the families GH16, GH39, GH50, GH86, and GH118. Among that, GH39, GH50, and GH86 belonged to clan GH-A, while the GH16 family belonged to clan GH-B. It was observed that GH16 is the largest polyspecific glycoside hydrolase family with ample number of β-agarases and the families GH50 and GH118 were found to be monospecific with only β-agarase activity. And, out of 84 non-catalytic carbohydrate-binding modules (CBMs), only CBM6 and CBM13 were professed in β-agarases. We witnessed a larger heterogeneity in molecular, physiochemical, and catalytic characteristics of the recombinant β-agarases including molecular mass: 32-132 kDa, optimum pH: 4.5-9, optimum temperature 16-60 °C, : 0.68-59.8 mg/ml, and : 0.781-11,400 U/mg. Owing to this extensive range of heterogeneity, they have lion's share in the multibillion dollar enzyme market. This review provides a holistic insight to a few aspects of recombinant β-agarases which can be referred by the upcoming explorers to this area.
琼脂酶（琼脂糖4-聚糖水解酶；EC 3.2.1.81）是一类属于糖苷水解酶（GH）家族的能够水解琼脂的酶。它们的分类取决于水解模式和产物形成。在所有琼脂酶中，β-琼脂酶及其作用形成的寡糖吸引了众多行业的关注。大量的β-琼脂酶基因已从藻类、海水和海洋沉积物等海洋来源中获得，将这些基因在合适的宿主中表达可产生重组β-琼脂酶。这些重组β-琼脂酶由于其在恶劣环境中提高的催化效率和稳定性以及易于大规模生产而具有广泛的工业应用。在本综述中，我们详细研究了不同类型的重组β-琼脂酶及其分子、物理化学和动力学性质，并突出了这些琼脂酶的显著特征。从2010年之后综述的文献中，我们发现重组β-琼脂酶属于GH16、GH39、GH50、GH86和GH118家族。其中，GH39、GH50和GH86属于GH-A族，而GH16家族属于GH-B族。据观察，GH16是最大的多特异性糖苷水解酶家族，有大量的β-琼脂酶，而GH50和GH118家族被发现是单特异性的，仅具有β-琼脂酶活性。并且，在84个非催化性碳水化合物结合模块（CBM）中，β-琼脂酶中仅发现了CBM6和CBM13模块。我们发现重组β-琼脂酶在分子、物理化学和催化特性方面存在较大的异质性，包括分子量：32 - 132 kDa、最适pH：4.5 - 9、最适温度16 - 60°C、Km：0.68 - 59.8 mg/ml以及kcat：0.781 - 11,400 U/mg。由于这种广泛的异质性，它们在数十亿美元的酶市场中占据了很大份额。本综述全面深入地介绍了重组β-琼脂酶的几个方面，可供该领域未来的探索者参考。
