纤维素酶与天然，自水解和工业木质素之间的相互作用以及聚山梨酯两亲物在减少非生产性结合中的作用,Biomacromolecules

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纤维素酶与天然，自水解和工业木质素之间的相互作用以及聚山梨酯两亲物在减少非生产性结合中的作用
Biomacromolecules ( IF 5.5 ) Pub Date : 2015-11-25 00:00:00 , DOI: 10.1021/acs.biomac.5b01203
Consuelo Fritz ₁ , Ana Ferrer ₁ , Carlos Salas ₁ , Hasan Jameel ₁ , Orlando J. Rojas _{1,

2}

Affiliation

在设计木质纤维素生物质生物转化策略时，了解酶与底物之间的相互作用至关重要。在这项研究中，我们通过使用石英晶体微重力法和表面等离子体共振，就地和实时地监测了分子事件，包括纤维素酶在木质素和纤维素上的吸附和解吸。还阐明了非离子表面活性分子的作用。考虑了在生物精炼中与糖平台有关的三种木质素底物，即硬木自水解纤维素（HWAH），硬木天然纤维素（MPCEL）和非木材天然纤维素（WSCEL）木质素。此外，衍生自软木（SWK）和硬木（HWK）的硫酸盐木质素也用作参考。结果表明，木质素与两者之间都具有高度亲和力，单组分和多组分酶。更重要的是，以高于其临界胶束浓度的浓度添加非离子表面活性剂可显着降低纤维素酶与木质素之间的非生产性相互作用（降低90％以上）。假定该作用是疏水键和氢键相互作用平衡的结果。此外，表面活性剂处理后表面粗糙度的降低和木质素表面的增加的润湿性导致与酶的亲和力降低。纤维素酶吸附在带有预吸附表面活性剂的木质素上时，观察到了纤维素酶的构象变化。对于天然纤维素分解木质素（MPCEL和WSCEL），在pH值介于4.8和5.5之间的水性介质中测定了弱的静电相互作用，从而观察到酶亲和力降低了约20％。这主要是由带电的木质素和纤维素酶之间的静电相互作用（渗透压效应）解释的。值得注意的是，非离子表面活性剂以纤维素纳米原纤维的形式吸附到纤维素上并没有影响其水解转化率。总的来说，我们的结果突出了非离子表面活性剂预处理在降低纤维素酶非生产性同时保持纤维素底物反应性方面的优势。

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Interactions between Cellulolytic Enzymes with Native, Autohydrolysis, and Technical Lignins and the Effect of a Polysorbate Amphiphile in Reducing Nonproductive Binding

Understanding enzyme–substrate interactions is critical in designing strategies for bioconversion of lignocellulosic biomass. In this study we monitored molecular events, in situ and in real time, including the adsorption and desorption of cellulolytic enzymes on lignins and cellulose, by using quartz crystal microgravimetry and surface plasmon resonance. The effect of a nonionic surface active molecule was also elucidated. Three lignin substrates relevant to the sugar platform in biorefinery efforts were considered, namely, hardwood autohydrolysis cellulolytic (HWAH), hardwood native cellulolytic (MPCEL), and nonwood native cellulolytic (WSCEL) lignin. In addition, Kraft lignins derived from softwoods (SWK) and hardwoods (HWK) were used as references. The results indicated a high affinity between the lignins with both, monocomponent and multicomponent enzymes. More importantly, the addition of nonionic surfactants at concentrations above their critical micelle concentration reduced remarkably (by over 90%) the nonproductive interactions between the cellulolytic enzymes and the lignins. This effect was hypothesized to be a consequence of the balance of hydrophobic and hydrogen bonding interactions. Moreover, the reduction of surface roughness and increased wettability of lignin surfaces upon surfactant treatment contributed to a lower affinity with the enzymes. Conformational changes of cellulases were observed upon their adsorption on lignin carrying preadsorbed surfactant. Weak electrostatic interactions were determined in aqueous media at pH between 4.8 and 5.5 for the native cellulolytic lignins (MPCEL and WSCEL), whereby a ∼20% reduction in the enzyme affinity was observed. This was mainly explained by electrostatic interactions (osmotic pressure effects) between charged lignins and cellulases. Noteworthy, adsorption of nonionic surfactants onto cellulose, in the form cellulose nanofibrils, did not affect its hydrolytic conversion. Overall, our results highlight the benefit of nonionic surfactant pretreatment to reduce nonproductive enzyme binding while maintaining the reactivity of the cellulosic substrate.

更新日期：2015-11-25

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