Structure-Based Rational and General Strategy for Stabilizing Single-Chain T-Cell Receptors to Enhance Affinity.

The T-cell receptor (TCR) is a crucial molecule in cellular immunity. The single-chain T-cell receptor (scTCR) is a potential format in TCR therapeutics because it eliminates the possibility of αß-TCR mispairing. However, its poor stability and solubility impede the in vitro study and manufacturing of therapeutic applications. In this study, some conserved structural motifs are identified in variable domains regardless of germlines and species. Theoretical analysis helps to identify those unfavored factors and leads to a general strategy for stabilizing scTCRs by substituting residues at exact IMGT positions with beneficial propensities on the consensus sequence of germlines. Several representative scTCRs are displayed to achieve stability optimization and retain comparable binding affinities with the corresponding αß-TCRs in the range of µM to pM. These results demonstrate that our strategies for scTCR engineering are capable of providing the affinity-enhanced and specificity-retained format, which are of great value in facilitating the development of TCR-related therapeutics.

A novel AA14 LPMO from Talaromyces rugulosus with bifunctional cellulolytic/hemicellulolytic activity boosted cellulose hydrolysis.

BACKGROUND: The recently discovered PcAA14A and B from white-rot basidiomycete Pycnoporus coccineus enriched our understanding of the oxidative degradation of xylan in fungi, however, the unusual mode of action of AA14 LPMOs has sparked controversy. The substrate specificity and functionality of AA14 LPMOs still remain enigmatic and need further investigation. RESULTS: In this study, a novel AA14 LPMO was characterized from the ascomycete Talaromyces rugulosus. TrAA14A has a broad substrate specificity with strong oxidative activity on pure amorphous cellulose and xyloglucan. It could simultaneously oxidize cellulose, xylan and xyloglucan in natural hemi/cellulosic substrate such as fibrillated eucalyptus pulp, and released native and oxidized cello-oligosaccharides, xylo-oligosaccharides and xyloglucan oligosaccharides from this substrate, but its cellulolytic/hemicellulolytic activity became weaker as the contents of xylan increase in the alkaline-extracted hemi/cellulosic substrates. The dual cellulolytic/hemicellulolytic activity enables TrAA14A to possess a profound boosting effect on cellulose hydrolysis by cellulolytic enzymes. Structure modelling of TrAA14A revealed that it exhibits a relatively flat active-site surface similar to the active-site surfaces in AA9 LPMOs but quite distinct from PcAA14B, despite TrAA14A is strongly clustered together with AA14 LPMOs. Remarkable difference in electrostatic potentials of L2 and L3 surfaces was also observed among TrAA14A, PcAA14B and NcLPMO9F. We speculated that the unique feature in substrate-binding surface might contribute to the cellulolytic/hemicellulolytic activity of TrAA14A. CONCLUSIONS: The extensive cellulolytic/hemicellulolytic activity on natural hemi/cellulosic substrate indicated that TrAA14A from ascomycete is distinctively different from previously characterized xylan-active AA9 or AA14 LPMOs. It may play as a bifunctional enzyme to decompose some specific network structures formed between cellulose and hemicellulose in the plant cell walls. Our findings shed new insights into the novel substrate specificities and biological functionalities of AA14 LPMOs, and will contribute to developing novel bifunctional LPMOs as the booster in commercial cellulase cocktails to efficiently break down the hemicellulose-cellulose matrix in lignocellulose.

Elucidating the Underlying Reactivities of Alternating Current Electrosynthesis by Time-Resolved Mapping of Short-Lived Reactive Intermediates.

Alternating current (AC) electrolysis is an emerging field in synthetic chemistry, however its mechanistic studies are challenged by the effective characterization of the elusive intermediate processes. Herein, we develop an operando electrochemical mass spectrometry platform that allows time-resolved mapping of stepwise electrosynthetic reactive intermediates in both direct current and alternating current modes. By dissecting the key intermediate processes of electrochemical functionalization of arylamines, the unique reactivities of AC electrosynthesis, including minimizing the over-oxidation/reduction through the inverse process, and enabling effective reaction of short-lived intermediates generated by oxidation and reduction in paired electrolysis, were evidenced and verified. Notably, the controlled kinetics of reactive N-centered radical intermediates in multistep sequential AC electrosynthesis to minimize the competing reactions was discovered. Overall, this work provides direct evidence for the mechanism of AC electrolysis, and clarifies the underlying reasons for its high efficiency, which will benefit the rational design of AC electrosynthetic reactions.

Si@nitrogen-doped porous carbon derived from covalent organic framework for enhanced Li-storage.

Due to ultra-high theoretical capacity (4200 mAh g-1), silicon (Si) is an excellent candidate for the anode of lithium-ion batteries (LIBs). However, the application of Si is severely limited by its volume expansion of approximately 300% during the charge/discharge process. Herein, nitrogen-doped porous carbon (NC) capped nano-Si particles (Si@NC) composites with a core-shell structure were obtained by calcination of covalent organic frameworks (COFs) encapsulated nano-Si. COFs is a crystalline material with well-ordered structures, adjustable and ordered pores and abundant N atoms. After carbonization, the well-ordered pores and frameworks were kept well. Compared with other Si@NC composites, the well-ordered NC framework shell derived from COFs possesses high elasticity and well-ordered pores, which provides space for the volume expansion of nano-Si, and a channel to transfer Li+. The core-shell Si@NC composite exhibited good performances when applied as the anode of LIBs. At a current density of 100 mA g-1, it exhibited a discharge-specific capacity of 1534.8 mAh g-1 after 100 cycles with a first-coulomb efficiency of 69.7%. The combination of COFs with nano-Si is a better strategy for the preparation of anode materials of LIBs.

Comparison of the Biochemical Properties and Roles in the Xyloglucan-Rich Biomass Degradation of a GH74 Xyloglucanase and Its CBM-Deleted Variant from Thielavia terrestris.

Xyloglucan is closely associated with cellulose and still retained with some modification in pretreated lignocellulose; however, its influence on lignocellulose biodegradation is less understood. TtGH74 from Thielavia terrestris displayed much higher catalytic activity than previously characterized fungal GH74 xyloglucanases. The carbohydrate-binding module 1 (CBM1) deleted variant (TtGH74ΔCBM) had the same optimum temperature and pH but an elevated thermostability. TtGH74 displayed a high binding affinity on xyloglucan and cellulose, while TtGH74ΔCBM completely lost the adsorption capability on cellulose. Their hydrolysis action alone or in combination with other glycoside hydrolases on the free xyloglucan, xyloglucan-coated phosphoric acid-swollen cellulose or pretreated corn bran and apple pomace was compared. CBM1 might not be essential for the hydrolysis of free xyloglucan but still effective for the associated xyloglucan to an extent. TtGH74 alone or synergistically acting with the CBH1/EG1 mixture was more effective in the hydrolysis of xyloglucan in corn bran, while TtGH74ΔCBM showed relatively higher catalytic activity on apple pomace, indicating that the role and significance of CBM1 are substrate-specific. The degrees of synergy for TtGH74 or TtGH74ΔCBM with the CBH1/EG1 mixture reached 1.22-2.02. The addition of GH10 xylanase in TtGH74 or the TtGH74ΔCBM/CBH1/EG1 mixture further improved the overall hydrolysis efficiency, and the degrees of synergy were up to 1.50-2.16.

Comparison of magnetic resonance imaging versus computed tomography-based thrombolysis treatment in patients with acute ischemic stroke.

PURPOSE: To evaluate the efficacy and safety of magnetic resonance imaging (MRI)-based comparing with computed tomography (CT)-based selection for intravenous thrombolysis in patients with acute ischemic stroke (AIS). METHODS: Totally 462 consecutive AIS patients treated with intravenous thrombolysis within a 4.5 h window from Jan. 2016 to Dec. 2019 were enrolled. The primary endpoint was the good functional outcome defined by a modified Rankin Scale (mRS) of 0-2 at 3 months. Secondary outcomes include the excellent functional outcome defined by a mRS of 0-1 at 3 months, occurrences of symptomatic intracranial hemorrhage (SICH), 7-day mortality, and 3-month mortality. RESULTS: Overall 172 patients received MRI and 290 received CT before they were treated with thrombolysis. The difference in the good or excellent functional outcome was not statistically significant between MRI and CT groups (both P > 0.05). The incidences of 7-day mortality (3.5% vs. 8.6%, P < 0.01), 30-day mortality (12.8% vs. 21.0%, P = 0.03), and SICH (12.2% vs. 20.3%, P < 0.01) were obviously lower for MRI-based regimen compared with CT-based regimen. Multivariate logistic regression indicated that MRI-based regimen was significantly associated with a lower risk of 7-day mortality (OR = 0.72, 95% CI: 0.53-0.91; P < 0.01), 30-day mortality (OR = 0.58, 95% CI: 0.47-0.73; P < 0.01), and SICH (OR = 0.44, 95% CI: 0.20-0.65; P < 0.01) after controlling for potential confounding factors. CONCLUSION: Despite MRI-based thrombolysis was not demonstrated to be associated with the good functional outcome, it significantly reduced risks of mortality and SICH in patients with AIS compared with CT-based thrombolysis.

Two C1-oxidizing AA9 lytic polysaccharide monooxygenases from Sordaria brevicollis differ in thermostability, activity, and synergy with cellulase.

Cellulolytic fungi usually have multiple genes for C1-oxidizing auxiliary activity 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) in their genomes, but their potential functional differences are less understood. In this study, two C1-oxidizing AA9 LPMOs, SbLPMO9A and SbLPMO9B, were identified from Sordaria brevicollis, and their differences, particularly in terms of thermostability, reducing agent specificity, and synergy with cellulase, were explored. The two enzymes exhibited weak binding to cellulose and intolerance to hydrogen peroxide. Their oxidative activity was influenced by cellulose crystallinity and surface morphology, and both enzymes tended to oxidize celluloses of lower crystallinity and high surface area. Comparably, SbLPMO9A had much better thermostability than SbLPMO9B, which may be attributed to the presence of a carbohydrate binding module 1 (CBM1)-like sequence at its C-terminus. In addition, the two enzymes exhibited different specificities and responsivities toward electron donors. SbLPMO9A and SbLPMO9B were able to boost the catalytic efficiency of endoglucanase I (EGI) on physically and chemically pretreated substrates but with different degrees of synergy. Substrate- and enzyme-specific synergism was observed by comparing the synergistic action of SbLPMO9A or SbLPMO9B with commercial Celluclast 1.5L on three kinds of cellulosic substrates. On regenerated amorphous cellulose and PFI (Papirindustriens Forskningsinstitut)-fibrillated bleached eucalyptus pulp, SbLPMO9B showed a higher synergistic effect than SbLPMO9A, while on delignified wheat straw, the synergistic effect of SbLPMO9A was higher than that of SbLPMO9B. On account of its excellent thermostability and boosting effect on the enzymatic hydrolysis of delignified wheat straw, SbLPMO9A may have high application potential in biorefineries for lignocellulosic biomass. KEY POINTS: • C1-oxidizing SbLPMO9A displayed higher thermostability than SbLPMO9B, probably due to the presence of a CBM1-like module. • The oxidative activity of the two SbLPMO9s on celluloses increased with decreasing cellulose crystallinity or increasing beating degree. • The two SbLPMO9s boosted the catalytic efficiency of cellulase, but the synergistic effect was substrate- and enzyme-specific.

Comparison of C4-oxidizing and C1/C4-oxidizing AA9 LPMOs in substrate adsorption, H2O2-driven activity and synergy with cellulase on celluloses of different crystallinity.

Two C1/C4-oxidizing AA9 lytic polysaccharide monooxygenases (AA9 LPMOs), AoLPMO9A and AoLPMO9B, and one C4-oxidizing AoLPMO9C from Aspergillus oryzae, were characterized and compared with the well-studied C4-oxidizing NcLPMO9C. NcLPMO9C and AoLPMO9C harboring carbohydrate-binding module 1 (CBM1) exhibited much stronger adsorption capacity than AoLPMO9A and B without CBM1. The binding affinity is crucial for the efficacy of H2O2 as cosubstrate and oxidative activity of AA9 LPMOs on crystalline cellulose. C4-oxidizing AA9 LPMOs had a striking boosting effect on cellobiohydrolase I (CBHI), while C1/C4-oxidizing AA9 LPMOs boosted CBHII and endoglucanase I (EGI) activity. Our results indicated that two types of AA9 LPMOs with different modularities and regioselectivities varied in cellulose adsorption, H2O2-driven activity and synergy with cellulase on celluloses of different crystallinity which could complement each other in lignocellulose degradation. C4-oxidizing AA9 LPMOs with CBM1 were particularly essential in cellulase cocktail due to high H2O2-driven activity and a striking boosting effect on CBHI.

Explicit Gain Equations for Hybrid Graphene-Quantum-Dot Photodetectors.

Graphene is an attractive material for broadband photodetection but suffers from weak light absorption. Coating graphene with quantum dots can significantly enhance light absorption and create extraordinarily high photogain. This high gain is often explained by the classical gain theory which is unfortunately an implicit function and may even be questionable. In this work, explicit gain equations for hybrid graphene-quantum-dot photodetectors are derived. Because of the work function mismatch, lead sulfide quantum dots coated on graphene will form a surface depletion region near the interface of quantum dots and graphene. Light illumination narrows down the surface depletion region, creating a photovoltage that gates the graphene. As a result, high photogain in graphene is observed. The explicit gain equations are derived from the theoretical gate transfer characteristics of graphene and the correlation of the photovoltage with the light illumination intensity. The derived explicit gain equations fit well with the experimental data, from which physical parameters are extracted.

A highly xyloglucan active lytic polysaccharide monooxygenase EpLPMO9A from Eupenicillium parvum 4-14 shows boosting effect on hydrolysis of complex lignocellulosic substrates.

The recently identified lytic polysaccharide monooxygenases (LPMOs) are important auxiliary proteins which contribute to lignocellulose biodegradation by oxidatively cleaving the glycosidic bonds in cellulose and other polysaccharides. The vast differences in terms of substrate specificity and regioselectivity within LPMOs provide us new possibilities to find promising candidates for the use in enzyme cocktails in biorefinery applications. In this study, a highly xyloglucan active family AA9 lytic polysaccharide monooxygenase EpLPMO9A was identified from Eupenicillium parvum 4-14. EpLPMO9A exhibited a mixed C1/C4 oxidative cleavage activity on cellulose and xyloglucan with a broad range of pH stability and good thermal stability at 40 °C. It showed a higher boosting effect on the enzymatic saccharification of complex lignocellulosic substrates associated with xyloglucan than on the lignocellulosic substrates without xyloglucan particularly in low commercial cellulase dosage cases. The oxidative cleavage of xyloglucan by EpLPMO9A may facilitate to open up the sterical hindrance of cellulose by xyloglucan and thereby increase accessibility for cellulase to lignocellulosic substrates. The discovery of more and more hemicellulose-active LPMOs and their contribution to breaking down the barriers by oxidatively acting on hemicellulose may expand our knowledge for their functions of LPMOs in lignocellulose biodegradation.

Explicit Gain Equations for Single Crystalline Photoconductors.

Photoconductors based on semiconducting thin films, nanowires, and two-dimensional atomic layers have been extensively investigated in the past decades. However, there is no explicit photogain equation that allows for fitting and designing photoresponses of these devices. In this work, we managed to derive explicit photogain equations for silicon nanowire photoconductors based on experimental observations. The silicon nanowires were fabricated by patterning the device layer of silicon-on-insulator wafers by standard lithography that were doped with boron at a concentration of ∼8.6 × 1017 cm-3. It was found that the as-fabricated silicon nanowires have a surface depletion region ∼32 nm wide. This depletion region protects charge carriers in the channel from surface scatterings, resulting in the independence of charge carrier mobilities on nanowire size. Under light illumination, the depletion region logarithmically narrows down, and the nanowire channel widens accordingly. Photo Hall effect measurements show that the nanowire photoconductance is not contributed by the increase of carrier concentrations but by the widening of the nanowire channel. As a result, a nanowire photoconductor can be modeled as a resistor in connection with floating Schottky junctions near the nanowire surfaces. Based on the photoresponses of a Schottky junction, we derived explicit photogain equations for nanowire photoconductors that are a function of light intensity and device physical parameters. The gain equations fit well with the experimental data, from which we extracted the minority carrier lifetimes as tens of nanoseconds, consistent with the minority carrier lifetime in nanowires reported in literature.

Toward Defect-Free Doping by Self-Assembled Molecular Monolayers: The Evolution of Interstitial Carbon-Related Defects in Phosphorus-Doped Silicon.

Self-assembled molecular monolayer (SAMM) doping on semiconductors has been widely appraised for its advantages of doping nanoelectronic devices for applications in the complementary metal-oxide-semiconductor transistor (CMOS) industry. However, defects introduced by SAMM-doping will limit the performance of the devices. Previously, we have found that SAMM-doping can bring carbon impurities into the silicon substrate and these unwanted carbon impurities can deactivate phosphorus dopants by forming an interstitial carbon (Ci)-substitutional phosphorus (Ci-Ps) complex. Herein, to develop a defect-free SAMM-doping process, the generation and annihilation of Ci-related defects are investigated by extending the thermal annealing time from 2 to 10 min using secondary ion mass spectrometry and deep-level transient spectroscopy. The results show that the concentration of Ci-related carbon defects is lower after a longer time of thermal annealing, although a longer annealing time actually introduces a higher concentration of carbon impurities into Si. This observation indicates that interstitial carbon evolves into substitutional carbon (Cs) that is electrically inactive during the thermal annealing process. A defect-free SAMM-doping process may be developed by an appropriate post-annealing process.

Manifestations of and risk factors for acute myocardial injury after acute organophosphorus pesticide poisoning.

This study aimed to explore the risk factors for acute myocardial injury (AMI) caused by acute organophosphorus pesticide poisoning (AOPP).The clinical data of 98 patients, who were treated in our hospital due to oral AOPP from April 2013 to April 2017, were retrospectively analyzed. These patients were divided into two groups: AMI group and control group. The incidence of AMI was analyzed. Furthermore, the dosage forms and dose of the pesticide, and the interval between pesticide taking and doctor visit were compared between these two groups. Moreover, their clinical symptoms were observed; the serum cholinesterase levels, myocardial injury, and heart failure markers were detected, and the occurrence of arrhythmia and the structure and function of the heart were investigated through continuous electrocardiographic monitoring and transthoracic echocardiography.Among these 98 AOPP patients, 51 patients were complicated with AMI, and the incidence was 52.0%. The main manifestations of these 51 patients with AMI were as follows: the serum levels of myocardial injury markers (creatine kinase-Mb [CK-Mb] and cardiac troponin I [cTnI]) and heart failure markers (N-terminal pro B-type natriuretic peptide [NT-pro BNP]) were significantly higher, when compared with the control group (P < .001), and the incidence of arrhythmia (FVPB, P = .02; RAA, P = .03; RVA, P = .02; ST-T changes, P = .01) and heart failure (P = .04) was also significantly higher when compared with the control group. With regard to dosage forms of the pesticides, the number of patients taking the pesticides with solvents containing aromatic hydrocarbons was significantly higher in the AMI group than in the control group (P = .001). And the number of patients taking over 100 mL of pesticides was also significantly higher in the AMI group than in the control group (P < .001). Significantly more patients in the AMI group had an interval of over 1 h between pesticide taking and doctor visit than in the control group (P < .001).Risk factors for AMI after AOPP may include the dose and dosage form of the pesticide, and the interval between pesticide taking and doctor visit.

Dynamics of Charge Carriers in Silicon Nanowire Photoconductors Revealed by Photo Hall Effect Measurements.

Photoconductors have extraordinarily high gain in quantum efficiency, but the origin of the gain has remained in dispute for decades. In this work, we employ photo Hall effect to reveal the gain mechanisms by probing the dynamics of photogenerated charge carriers in silicon nanowire photoconductors. The results reveal that a large number of photogenerated minority electrons are localized in the surface depletion region and surface trap states. The same number of excess hole counterparts is left in the nanowire conduction channel, resulting in the fact that excess holes outnumber the excess electrons in the nanowire conduction channel by orders of magnitude. The accumulation of the excess holes broadens the conduction channel by narrowing down the depletion region, which leads to the experimentally observed high photo gain.

Deep level transient spectroscopic investigation of phosphorus-doped silicon by self-assembled molecular monolayers.

It is known that self-assembled molecular monolayer doping technique has the advantages of forming ultra-shallow junctions and introducing minimal defects in semiconductors. In this paper, we report however the formation of carbon-related defects in the molecular monolayer-doped silicon as detected by deep-level transient spectroscopy and low-temperature Hall measurements. The molecular monolayer doping process is performed by modifying silicon substrate with phosphorus-containing molecules and annealing at high temperature. The subsequent rapid thermal annealing drives phosphorus dopants along with carbon contaminants into the silicon substrate, resulting in a dramatic decrease of sheet resistance for the intrinsic silicon substrate. Low-temperature Hall measurements and secondary ion mass spectrometry indicate that phosphorus is the only electrically active dopant after the molecular monolayer doping. However, during this process, at least 20% of the phosphorus dopants are electrically deactivated. The deep-level transient spectroscopy shows that carbon-related defects are responsible for such deactivation.

Rutile TiO2 Mesocrystals as Sulfur Host for High-Performance Lithium-Sulfur Batteries.

Although lithium-sulfur (Li-S) batteries are among the most promising rechargeable batteries in the field of energy-storage devices, their poor cycling performance restricts their potential applications. Polar materials can improve the cycling stability owing to their inherent strong chemical interaction with polysulfides. Herein, novel rutile TiO2 mesocrystals (RTMs) are employed as the host for sulfur in Li-S batteries; the RTMs display a stable cycling performance with a capacity retention of 64 % and a small average capacity decay rate of 0.12 % per cycle over 300 cycles at 1 C rate. The good electrochemical properties are attributed to the interior ordered nanopores of the RTMs, which can effectively limit the dissolution of polysulfides, and the ultrafine nanowires in RTMs, which shorten the path for lithium-ion transport effectively.

Characterization of the Wild-Type and Truncated Forms of a Neutral GH10 Xylanase from Coprinus cinereus: Roles of C-Terminal Basic Amino Acid-Rich Extension in Its SDS Resistance, Thermostability, and Activity.

A neutral xylanase (CcXyn) was identified from Coprinus cinereus. It has a single GH10 catalytic domain with a basic amino acid-rich extension (PVRRK) at the C-terminus. In this study, the wild-type (CcXyn) and C-terminus-truncated xylanase (CcXyn-Δ5C) were heterologously expressed in Pichia pastoris and their characteristics were comparatively analyzed with aims to examine the effect of this extension on the enzyme function. The circular dichorism analysis indicated that both enzymes in general had a similar structure, but CcXyn-Δ5C contained less α-helices (42.9%) and more random coil contents (35.5%) than CcXyn (47.0% and 32.8%, respectively). Both enzymes had the same pH (7.0) and temperature (45°C) optima, and similar substrate specificity on different xylans. They all hydrolyzed beechwood xylan primarily to xylobiose and xylotriose. The amounts of xylobiose and xylotriose accounted for 91.5% and 92.2% (w/w) of total xylooligosaccharides (XOS) generated from beechwood by CcXyn and CcXyn-Δ5C, respectively. However, truncation of the C-terminal 5-amino-acids extension significantly improved the thermostability, SDS resistance, and pH stability at pH 6.0-9.0. Furthermore, CcXyn-Δ5C exhibited a much lower Km value than CcXyn (0.27 mg/ml vs 0.83 mg/ml), and therefore, the catalytic efficiency of CcXyn-Δ5C was 2.4-times higher than that of CcXyn. These properties make CcXyn-Δ5C a good model for the structure-function study of (α/ß)8-barrel-folded enzymes and a promising candidate for various applications, especially in the detergent industry and XOS production.

N- and C-terminal truncations of a GH10 xylanase significantly increase its activity and thermostability but decrease its SDS resistance.

XynII from Volvariella volvacea has high sodium dodecyl sulfate (SDS) resistance, with the potential for industrial applications under harsh conditions. It consists of a single glycoside hydrolase family 10 (GH10) catalytic domain but contains an additional unique 10 and 4 amino acid residues at the N- and C-terminus, respectively. In this study, five XynII derivatives with N- and/or C-terminus deletions were constructed to determine the effects of these regions on enzyme activity, substrate specificity, thermostability, and SDS resistance. Our results revealed that N- and/or C-terminal truncations significantly increased enzyme activity and thermostability, but reduced SDS resistance. Specifically, the XynIIΔNC4 mutant had 2.53-fold more catalytic efficiency (k cat/K m) towards beechwood xylan than wild-type and 3.0-fold more thermostability (t 1/2 [55°C]). XynIIΔNC4 displayed 3.33-, 4.38-, 1.37-, and 1.98-fold more activity against xylotriose, xylotetraose, xylopentaose, and xylohexaose, respectively, than XynII did. However, its half-life (t 1/2) in 4 % SDS was only 1.72 h, while that of XynII was 4.65 h. Circular dichroism analysis revealed that deletion of N- and C-terminal segments caused minor changes in secondary structure. Our observations suggest that the extra N- and C-terminal segments in wild-type XynII evolved to strengthen the interaction between these regions of the protein, making the local structure more rigid and reducing structural flexibility. In this way, N- and C-terminal truncations increased the thermostability and activity of XynII on different xylans and linear xylooligosaccharides, but reduced its resistance to SDS.