Adsorption of Enzyme Onto Lignins of Liquid Hot Water Pretreated Hardwoods
Adsorption of Enzyme Onto Lignins of Liquid Hot Water Pretreated Hardwoods
复制标题
DOI：
10.1002/bit.25359
复制
发表时间：
2015-03-01
影响因子：
3.8
通讯作者：
Ladisch, Michael R.
中科院分区：
文献类型：
--
作者：
Ko, Ja Kyong;Ximenes, Eduardo;Ladisch, Michael R.
纤维素酶在木质素上的吸附被证明是非生产性的，因此减少了液体热水预处理的纤维素的酶水解。在里氏木霉纤维素酶混合物的酶成分中，β-葡萄糖苷酶对木质素的吸附最强。仅2-18%的初始β-葡萄糖苷酶活性保留在上清液中，而与木质素一起孵育后恢复了50-60%的纤维二糖水解酶和内切葡聚糖酶活性。通过将 pH 值提高至 5.5 并添加 NaCl 至 200mM，上清液中的游离酶增加，但水解并未增强，因为酶水解的最佳 pH 值为 4.8。静电相互作用有助于酶吸附，其效果对于具有高分子量（78-94kDa）和高等电点（pI 5.7-6.4）的里氏木霉-葡萄糖苷酶最为明显。由于协同水解纤维素所需的酶组分具有不同的特征（分子量、疏水性和pI），它们与木质素表现出不同的吸附行为，从而改变纤维素水解过程中协同水解所需的酶活性的比例。来自黑曲霉的β-葡萄糖苷酶表现出比来自里氏木霉的β-葡萄糖苷酶更少的吸附。在酶混合物中补充添加黑曲霉-葡萄糖苷酶可使预处理硬木的水解增加两倍。本文的分析表明，愈创木基含量较高的木质素会吸附更多的纤维素酶，特别是β-葡萄糖苷酶，并且木质素上β-葡萄糖苷酶的吸附间接抑制了预处理硬木中纤维素的酶水解，因为纤维二糖的水解减少，进而积累并抑制CBH。生物技术。生物工程。 2015；112：447-456。 (c) 2014 年 Wiley 期刊公司。
The adsorption of cellulase enzymes onto lignin is shown to be non-productive and therefore reduces enzymatic hydrolysis of liquid hot water pretreated cellulose. Among the enzyme components of Trichoderma reesei cellulase cocktail, -glucosidase showed the strongest adsorption onto lignin. Only 2-18% of the initial -glucosidase activity remained in the supernatant while 50-60% of cellobiohydrolase and endoglucanase activities were recovered after incubation with lignin. By increasing the pH to 5.5 and adding NaCl to a 200mM, the free enzymes in the supernatant were increased but hydrolysis was not enhanced since optimal pH for enzymatic hydrolysis is at 4.8. Electrostatic interactions contributed to enzyme adsorption and their effect was most pronounced for T. reesei -glucosidase which had high molecular weights (78-94kDa) and high isoelectric points (pI 5.7-6.4). Since the enzyme components which are required to synergistically hydrolyze cellulose have different profiles (molecular weight, hydrophobicity and pI), they exhibit different adsorption behaviors with lignin, and thereby change the ratio of enzyme activities needed for synergism during cellulose hydrolysis. -glucosidase from Aspergillus niger exhibits less adsorption than -glucosidase from T. reesei. Supplemental addition of A. niger -glucosidase to the enzyme mixture increases hydrolysis of pretreated hardwood by a factor of two. The analysis presented in this paper shows that lignins with higher guaiacyl content adsorb more cellulase enzymes, particularly -glucosidase, and that adsorption of -glucosidase onto lignin indirectly suppresses enzymatic hydrolysis of cellulose in pretreated hardwoods due to decreased hydrolysis of cellobiose which in turn accumulates and inhibits CBH. Biotechnol. Bioeng. 2015;112: 447-456. (c) 2014 Wiley Periodicals, Inc.