Enzymatically Debranched Xylans in Graft Copolymerization

Valorization of Grain and Oil By-Products with Special Focus on Hemicellulose Modification

Hemicellulose is one of the most important natural polysaccharides in nature. Hemicellulose from different sources varies in chemical composition and structure, which in turn affects the modification effects and industrial applications. Grain and oil by-products (GOBPs) are important raw materials for hemicellulose. This article reviews the modification methods of hemicellulose in GOBPs. The effects of chemical and physical modification methods on the properties of GOBP hemicellulose biomaterials are evaluated. The potential applications of modified GOBP hemicellulose are discussed, including its use in film production, hydrogel formation, three-dimensional (3D) printing materials, and adsorbents for environmental remediation. The limitations and future recommendations are also proposed to provide theoretical foundations and technical support for the efficient utilization of these by-products.

Arabinoxylans matrixes as a potential material for drug delivery systems development - A bibliometric analysis and literature review

Arabinoxylans (AX) have become a focal point in the pharmaceutical sector owing to their physicochemical, biological, and functional properties. The purpose of this paper was to present a summary of the utilization of AX as drug release matrices through a bibliometric analysis (BA) and a literature review to spotlight the AX functional characteristics and their technological applications to promote this line of research. The BA was carried out using data from a Web of Science database research, specifically emphasizing the analysis of authors' keywords. This approach was chosen due to its significance in comprehensively understanding a particular research field and its relevance for in-depth knowledge of a research field. The BA outcomes revealed limited information concerning the AX applications in both release matrices and as excipients in the formulation and development of drug delivery systems (DDS), so there is a need for additional scientific and technological research in these areas to address the existing information gaps. However, the literature review shows that the native and modified AX from different delivery release systems, such as macrogels (including films, tablets, and hard gelatin capsules) and multi-particulate systems (including micro and nanogels), present an excellent potential as release matrices of biomolecules and drugs, such as doxorubicin, diclofenac sodium, caffeine, gentamicin, tizanidine hydrochloride, and insulin. In conclusion, AX have a wide potential for application in the pharmaceutical industry, so this work is expected to be a reference point for future research by scientists, technologists, and entrepreneurs who cope with the subject.

Enzymatic upgrading of heteroxylans for added-value chemicals and polymers

Xylan is one of the most abundant, natural polysaccharides, and much recent interest focuses on upgrading heteroxylan to make use of its unique structures and chemistries. Significant progress has been made in the discovery and application of novel enzymes for debranching and modifying heteroxylans. Debranching enzymes include acetylxylan esterases, α-l-arabinofuranosidases and α-dglucuronidases that release side groups from the xylan backbone to recover both biochemicals and less substituted xylans for polymer applications in food packaging or drug delivery systems. Besides esterases and hydrolases, many oxidoreductases including carbohydrate oxidases, lytic polysaccharide monooxygenases, laccases and peroxidases have been also applied to alter different types of xylans for improved physical and chemical properties. This review will highlight the recent discovery and application of enzymes for upgrading xylans for use as added-value chemicals and in functional polymers.

A novel acetyl xylan esterase enabling complete deacetylation of substituted xylans

BACKGROUND

Acetylated 4-O-(methyl)glucuronoxylan (GX) is the main hemicellulose in deciduous hardwood, and comprises a β-(1→4)-linked xylopyranosyl (Xylp) backbone substituted by both acetyl groups and α-(1→2)-linked 4-O-methylglucopyranosyluronic acid (MeGlcpA). Whereas enzymes that target singly acetylated Xylp or doubly 2,3-O-acetyl-Xylp have been well characterized, those targeting (2-O-MeGlcpA)3-O-acetyl-Xylp structures in glucuronoxylan have remained elusive.

RESULTS

An unclassified carbohydrate esterase (FjoAcXE) was identified as a protein of unknown function from a polysaccharide utilization locus (PUL) otherwise comprising carbohydrate-active enzyme families known to target xylan. FjoAcXE was shown to efficiently release acetyl groups from internal (2-O-MeGlcpA)3-O-acetyl-Xylp structures, an activity that has been sought after but lacking in known carbohydrate esterases. FjoAcXE action boosted the activity of α-glucuronidases from families GH67 and GH115 by five and nine times, respectively. Moreover, FjoAcXE activity was not only restricted to GX, but also deacetylated (3-O-Araf)2-O-acetyl-Xylp of feruloylated xylooligomers, confirming the broad substrate range of this new carbohydrate esterase.

CONCLUSION

This study reports the discovery and characterization of the novel carbohydrate esterase, FjoAcXE. In addition to cleaving singly acetylated Xylp, and doubly 2,3-O-acetyl-Xylp, FjoAcXE efficiently cleaves internal 3-O-acetyl-Xylp linkages in (2-O-MeGlcpA)3-O-acetyl-Xylp residues along with densely substituted and branched xylooligomers; activities that until now were missing from the arsenal of enzymes required for xylan conversion.