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|Stability:||> 10 years under recommended storage conditions|
|Main Chain Glycosidic Linkage:||β-1,4|
|Substrate For (Enzyme):||Acetylxylan esterase|
High purity Xylan (Birchwood, partially acetylated) for use in research, biochemical enzyme assays and in vitro diagnostic analysis.
Quantification of morphochemical changes during in situ enzymatic hydrolysis of individual biomass particles based on autofluorescence imaging.
Kapsokalyvas, D., Loos, J., Boogers, I. A. L. A., Appeldoorn, M. M., Kabel, M. A. & Zandvoort, M. V. (2019). Biopolymers, 111(3), e23347.
Enzymatic hydrolysis of biomass is an established method for producing biofuels. Lignocellulosic biomass such as corn stover is very inhomogeneous material with big variation on conversion rates between individual particles therefore leading to variable recalcitrance results. In this study, we used noninvasive optical microscopy techniques, such as two‐photon microscopy and fluorescence lifetime imaging microscopy, to visualize and analyze morphological and chemical changes of individual corn stover particles pretreated with sulfuric acid during hydrolysis. Morphochemical changes were interpreted based on the fluorescence properties of isolated building blocks of plant cell wall, such as cellulose, hemicellulose, and lignin. Enzymatic hydrolysis resulted in particle size reduction, side wall collapse, decrease of second harmonic signal from cellulose, redshifting of autofluorescence emission, and lifetime decrease attributed to the relative increase of lignin. Based on these observations, tracking compositional change after hydrolysis of individual particles was accomplished. The methodologies developed offer a paradigm for imaging and analyzing enzymatic hydrolysis in vitro and in situ, which could be used for screening enzymes cocktails targeting specific recalcitrant structures or investigating locally enzyme anti‐inhibitory agents.Hide Abstract
Highly Efficient Degradation of Xylan into Xylose by a Single Enzyme.
Basit, A., Miao, T., Liu, J., Wen, J., Song, L., Zheng, F., Lou, H. & Jiang, W. (2019). ACS Sustainable Chemistry & Engineering, 7(13), 11360-11368.
Here, we report highly efficient degradation of xylan into xylose by a single multifunctional xylanolytic enzyme from the filamentous fungus Thermothelomyces thermophila (termed Ttxy43). Ttxy43 shows three different enzyme activities toward carbohydrates, β-xylosidase (80.8 U/mg), endoxylanase (105.42 U/mg), and α-l-arabinofuranosidase enzyme activities (15.81 U/mg). Analysis of the catalytic mode of action of Ttxy43 for birchwood-xylan (BWX) reveals that endoxylanase initially degrades xylan to unbranched xylooligosaccharides (XOSs) (xylobiose, xylotriose, xylotetraose) as intermediates, which are then quickly hydrolyzed into single xylose by β-xylosidase. Site-directed mutagenesis studies indicate that Ttxy43 residues Asp134 and Glu228 are essential catalytic sites, while Glu176, Asp38, and Asp85 play an accessory role. More importantly, Ttxy43 displays higher degradation efficiency in comparison with a commercial β-xylosidase and endoxylanase “cocktail”. These findings elucidate an efficient integrated degradation mechanism of xylan under industrial reaction conditions, which provides a novel strategy to design techniques for biomass energy production.Hide Abstract
Structural and functional characterization of a bifunctional GH30-7 xylanase B from the filamentous fungus Talaromyces cellulolyticus.
Nakamichi, Y., Fouquet, T., Ito, S., Watanabe, M., Matsushika, A. & Inoue, H. (2019). Journal of Biological Chemistry, 294(11), 4065-4078.
Glucuronoxylanases are endo-xylanases and members of the glycoside hydrolase family 30 subfamilies 7 (GH30-7) and 8 (GH30-8). Unlike for the well-studied GH30-8 enzymes, the structural and functional characteristics of GH30-7 enzymes remain poorly understood. Here, we report the catalytic properties and three-dimensional structure of GH30-7 xylanase B (Xyn30B) identified from the cellulolytic fungus Talaromyces cellulolyticus. Xyn30B efficiently degraded glucuronoxylan to acidic xylooligosaccharides (XOSs), including an α-1,2-linked 4-O-methyl-D-glucuronosyl substituent (MeGlcA). Rapid analysis with negative-mode electrospray-ionization multistage MS (ESI(−)-MSn) revealed that the structures of the acidic XOS products are the same as those of the hydrolysates (MeGlcA2Xyln, n > 2) obtained with typical glucuronoxylanases. Acidic XOS products were further degraded by Xyn30B, releasing first xylobiose and then xylotetraose and xylohexaose as transglycosylation products. This hydrolase reaction was unique to Xyn30B, and the substrate was cleaved at the xylobiose unit from its nonreducing end, indicating that Xyn30B is a bifunctional enzyme possessing both endo-glucuronoxylanase and exo-xylobiohydrolase activities. The crystal structure of Xyn30B was determined as the first structure of a GH30-7 xylanase at 2.25 Å resolution, revealing that Xyn30B is composed of a pseudo-(α/β)8-catalytic domain, lacking an α6 helix, and a small β-rich domain. This structure and site-directed mutagenesis clarified that Arg46, conserved in GH30-7 glucuronoxylanases, is a critical residue for MeGlcA appendage-dependent xylan degradation. The structural comparison between Xyn30B and the GH30-8 enzymes suggests that Asn93 in the β2-α2 loop is involved in xylobiohydrolase activity. In summary, our findings indicate that Xyn30B is a bifunctional endo- and exo-xylanase.Hide Abstract
Structural and biochemical characterization of the Cutibacterium acnes exo-β-1,4-mannosidase that targets the N-glycan core of host glycoproteins.
Reichenbach, T., Kalyani, D., Gandini, R., Svartström, O., Aspeborg, H. & Divne, C. (2018). PloS One, 13(9), e0204703.
Commensal and pathogenic bacteria have evolved efficient enzymatic pathways to feed on host carbohydrates, including protein-linked glycans. Most proteins of the human innate and adaptive immune system are glycoproteins where the glycan is critical for structural and functional integrity. Besides enabling nutrition, the degradation of host N-glycans serves as a means for bacteria to modulate the host’s immune system by for instance removing N-glycans on immunoglobulin G. The commensal bacterium Cutibacterium acnes is a gram-positive natural bacterial species of the human skin microbiota. Under certain circumstances, C. acnes can cause pathogenic conditions, acne vulgaris, which typically affects 80% of adolescents, and can become critical for immunosuppressed transplant patients. Others have shown that C. acnes can degrade certain host O-glycans, however, no degradation pathway for host N-glycans has been proposed. To investigate this, we scanned the C. acnes genome and were able to identify a set of gene candidates consistent with a cytoplasmic N-glycan-degradation pathway of the canonical eukaryotic N-glycan core. We also found additional gene sequences containing secretion signals that are possible candidates for initial trimming on the extracellular side. Furthermore, one of the identified gene products of the cytoplasmic pathway, AEE72695, was produced and characterized, and found to be a functional, dimeric exo-β-1,4-mannosidase with activity on the β-1,4 glycosidic bond between the second N-acetylglucosamine and the first mannose residue in the canonical eukaryotic N-glycan core. These findings corroborate our model of the cytoplasmic part of a C. acnes N-glycan degradation pathway.Hide Abstract