Xylan degradation improved by a combination of monolithic columns bearing immobilized recombinant β-xylosidase from Aspergillus awamori X-100 and Grindamyl H121 β-xylanase

Efficient and rapid digestion of proteins with a dual-enzyme microreactor featuring 3-D pores formed by dopamine/polyethyleneimine/acrylamide-coated KIT-6 molecular sieve

The microreactor with two types of immobilized enzymes, exhibiting excellent orthogonal performance, represents an effective approach to counteract the reduced digestion efficiency resulting from the absence of a single enzyme cleavage site, thereby impacting protein identification. In this study, we developed a hydrophilic dual-enzyme microreactor characterized by rapid mass transfer and superior enzymatic activity. Initially, we selected KIT-6 molecular sieve as the carrier for the dual-IMER due to its three-dimensional network pore structure. Modification involved co-deposition of polyethyleneimine (PEI) and acrylamide (AM) as amine donors, along with dopamine to enhance material hydrophilicity. Remaining amino and double bond functional groups facilitated stepwise immobilization of trypsin and Glu-C. Digestion times for bovine serum albumin (BSA) and bovine hemoglobin (BHb) on the dual-IMER were significantly reduced compared to solution-based digestion (1 min vs. 36 h), resulting in improved sequence coverage (91.30% vs. 82.7% for BSA; 90.24% vs. 89.20% for BHb). Additionally, the dual-IMER demonstrated excellent durability, retaining 96.08% relative activity after 29 reuse cycles. Enhanced protein digestion efficiency can be attributed to several factors: (1) KIT-6's large specific surface area, enabling higher enzyme loading capacity; (2) Its three-dimensional network pore structure, facilitating faster mass transfer and substance diffusion; (3) Orthogonality of trypsin and Glu-C enzyme cleavage sites; (4) The spatial effect introduced by the chain structure of PEI and glutaraldehyde's spacing arm, reducing spatial hindrance and enhancing enzyme-substrate interactions; (5) Mild and stable enzyme immobilization. The KIT-6-based dual-IMER offers a promising technical tool for protein digestion, while the PDA/PEI/AM-KIT-6 platform holds potential for immobilizing other proteins or active substances.

Structures, Biochemical Characteristics, and Functions of β-Xylosidases

The complete degradation of abundant xylan derived from plants requires the participation of β-xylosidases to produce the xylose which can be converted to xylitol, ethanol, and other valuable chemicals. Some phytochemicals can also be hydrolyzed by β-xylosidases into bioactive substances, such as ginsenosides, 10-deacetyltaxol, cycloastragenol, and anthocyanidins. On the contrary, some hydroxyl-containing substances such as alcohols, sugars, and phenols can be xylosylated by β-xylosidases into new chemicals such as alkyl xylosides, oligosaccharides, and xylosylated phenols. Thus, β-xylosidases shows great application prospects in food, brewing, and pharmaceutical industries. This review focuses on the molecular structures, biochemical properties, and bioactive substance transformation function of β-xylosidases derived from bacteria, fungi, actinomycetes, and metagenomes. The molecular mechanisms of β-xylosidases related to the properties and functions are also discussed. This review will serve as a reference for the engineering and application of β-xylosidases in food, brewing, and pharmaceutical industries.

Macroporous Polymer Monoliths for Affinity Chromatography and Solid-Phase Enzyme Processing

Nowadays, monolithic stationary phases, because of their special morphology and enormous permeability, are widely used for the development and realization of fast dynamic and static processes based on the mass transition between liquid and solid phases. These are liquid chromatography, solid-phase synthesis, microarrays, flow-through enzyme reactors, etc. High-performance liquid chromatography on monoliths, including the bioaffinity mode, represents unique technique appropriate for fast and efficient separation of biological (macro)molecules of different sizes and shapes (proteins, nucleic acids, peptides), as well as such supramolecular systems as viruses.In the edited chapter, the examples of the application of commercially available macroporous monoliths for modern affinity processing are presented. In particular, the original methods developed for efficient isolation and fractionation of monospecific antibodies from rabbit blood sera, the possibility of simultaneous affinity separation of protein G and serum albumin from human serum, the isolation of recombinant products, such as protein G and tissue plasminogen activator, respectively, are described in detail. The suggested and realized multifunctional fractionation of polyclonal pools of antibodies by the combination of several short monolithic columns (disks) with different affinity functionalities stacked in the same cartridge represents the original and practically valuable method that can be used in biotechnology. In addition, macroporous monoliths were adapted to the immobilization of such different enzymes as polynucleotide phosphorylase, ribonuclease A, α-chymotrypsin, chitinolytic biocatalysts, β-xylosidase, and β-xylanase. The possibility of use of immobilized enzyme reactors based on monoliths for different purposes is demonstrated.