Glucose oxidase (GOD) is an oxygen-consuming dehydrogenase that can catalyze the production of gluconic acid hydrogen peroxide from glucose, and its specific mechanism of action makes it promising for applications, while the low catalytic activity and poor thermostability have become the main factors limiting the industrial application of this enzyme. In this study, we used the glucose oxidase AtGOD reported with the best thermostability as the source sequence for phylogenetic analysis to obtain the GOD with excellent performance. Six genes were screened and successfully synthesized for functional validation. Among them, the glucose oxidase AhGODB derived from Aspergillus heteromorphus was expressed in Pichia pastoris and showed better thermostability and catalytic activity, with an optimal temperature of 40 ℃, a specific activity of 112.2 U/mg, and a relative activity of 47% after 5 min of treatment at 70 ℃. To improve its activity and thermal stability, we constructed several mutants by directed evolution combined with rational design. Compared with the original enzyme, the mutant T72R/A153P showcased the optimum temperature increasing from 40 to 50 ℃, the specific activity increasing from 112.2 U/mg to 166.1 U/mg, and the relative activity after treatment at 70 ℃ for 30 min increasing from 0% to 33%. In conclusion, the glucose oxidase mutants obtained in this study have improved catalytic activity and thermostability, and have potential for application.
Glucose Oxidase/chemistry* ; Enzyme Stability ; Aspergillus/genetics* ; Pichia/metabolism* ; Temperature ; Catalysis ; Fungal Proteins/metabolism* ; Hot Temperature

Sweet-tasting proteins demonstrate application potential in foods and beverages due to their high sweetness, low calorie, and non-toxicity. So far, eight natural sweet-tasting proteins have been obtained from natural plants. This paper briefs the sweetness properties of the eight proteins and the molecular mechanism of the sweetness, reviews the progress in the genetic engineering, heterologous expression, and molecular modification of three representative sweet-tasting proteins (monellin, brazzein, and thaumatin), and summarizes their expression yields in different hosts and sweetness properties. Lastly, this paper prospects the research, application, and industrial development of sweet-tasting proteins. This review provides a reference for further research and development of new proteinaceous sweeteners.
Plant Proteins/biosynthesis* ; Genetic Engineering/methods* ; Sweetening Agents/chemistry* ; Plants, Genetically Modified/metabolism*

Computational modeling is an invaluable tool for mechanism analysis, directed engineering, and rational design of biological parts, metabolic networks, and even cellular systems. It can provide new technological solutions to address biological challenges at different levels and has become a central focus of research in biomanufacturing. In the computational modeling of proteins, which are the key parts in biological systems, the traditional physics-based methods (computer software and mathematical model) have been widely used to study the physical and chemical processes in the functioning of proteins, and have thus been recognized as a powerful tool for understanding complex biological systems and guiding experimental designs. As the scale of computational modeling continues to expand, traditional modeling techniques face difficulties in balancing computational accuracy and speed. In recent years, the explosive growth of biological data has made it possible to construct high-performance artificial intelligence (AI) models, which brings new opportunities to the computational modeling of proteins, and the AI-enhanced physics-based computational modeling technologies have emerged. This combined strategy not only incorporates the chemical knowledge and established physical principles but also is powerful in data processing and pattern recognition, which greatly improves the computational efficiency and prediction accuracy, as well as possesses stronger interpretation ability, transferability, and robustness. The AI-enhanced physics-based computational modeling technologies have already shown great potential and value in biocatalysis, paving a new way for the future development of biomanufacturing.
Artificial Intelligence ; Proteins/chemistry* ; Computer Simulation ; Software ; Computational Biology/methods*

Predicting protein mutation effects is a key challenge in bioinformatics and protein engineering. Recent advancements in deep learning, particularly the development of protein language models (PLMs), have brought new opportunities to this field. This review summarizes the application of PLMs in predicting protein mutation effects, focusing on three main types of models: sequence-based models, structure-based models, and models that combine sequence and structural information. We analyze in detail the principles, advantages, and limitations of these models and discuss the application of unsupervised and supervised learning in model training. Furthermore, this paper discusses the main challenges currently faced, including the acquisition of high-quality datasets and the handling of data noise. Finally, we look ahead to future research directions, including the application prospects of emerging technologies such as multimodal fusion and few-shot learning. This review aims to provide researchers with a comprehensive perspective to further advance the prediction of protein mutation effects.
Mutation ; Proteins/chemistry* ; Computational Biology/methods* ; Deep Learning ; Protein Engineering

Endotoxins are common exogenous pyrogens. Excessive endotoxins in medical devices and injections can lead to serious consequences such as sepsis, septic shock, and even death. Therefore, endotoxin detection plays a crucial role in medical, pharmaceutical, and food sectors. The wide application of Limulus amebocyte lysate (LAL) has led to a sharp decline in the number of horseshoe crabs. Moreover, the LAL assay has limitations such as interbatch variations and difficulty in quantification. The recombinant factor C (rFC) assay is stable between batches, highly sensitive, and capable of quantitation, and thus it can be used as an alternative for the LAL assay. However, the high cost and complex procedures involved in producing recombinant factor C have limited the widespread application of this method. In order to simplify the preparation and reduce the production cost of recombinant factor C, this study focuses on the production of recombinant factor C based on the baculovirus expression system. Multiple measures such as a high-yield and anti-apoptotic vector qBac-IIIG, the optimal signal peptide, and the optimized codon were used to reach the goal of endotoxin detection with cell supernatant. This method simplifies the steps of protein purification. The sensitivity of the supernatant reached 0.05 EU/mL in a 1-L fermentation system, and 500 000 detecting reactions can be supported per liter of fermentation broth. This study increases the yield and activity of recombinant factor C, simplifies the procedures of protein purification, and reduces the cost, laying a foundation for the promotion and application of recombinant factor C in endotoxin detection.
Animals ; Recombinant Proteins/genetics* ; Horseshoe Crabs/chemistry* ; Baculoviridae/metabolism* ; Endotoxins/analysis* ; Protein C/biosynthesis* ; Genetic Vectors/genetics* ; Arthropod Proteins/genetics* ; Enzyme Precursors ; Serine Endopeptidases

This study aims to establish a high-performance size-exclusion chromatography (HPSEC) method for determining the content of the classical swine fever virus (CSFV) E2 protein and screen the optimal stabilizer to enhance the stability of this protein. The optimal detection conditions were determined by optimizing the composition of the mobile phase, and characteristic chromatographic peaks were identified by SDS-PAGE and Western blotting. The specificity, repeatability, precision, linearity, limit of detection (LOD), and limit of quantitation (LOQ) of the method were assessed. The method established was used to determine the content of CSFV E2 protein antigen and vaccine. Differential scanning fluorimetry (DSF) was employed to screen the buffer system, pH, and salt ion concentrations, and sugar, amino acid, and alcohol stabilizers were further screened. The results showed that using a 200 mmol/L phosphate buffer provided the best column efficiency. An antigen-specific chromatographic peak appeared at the retention time of 18 min, which was identified as the CSFV E2 protein by SDS-PAGE and Western blotting. The method exhibited high specificity for detecting the CSFV E2 protein, with no absorbance peak observed in the blank control. The relative standard deviation (RSD) of the peak area for six repeated injections of the CSFV E2 protein was 0.74%, indicating good repeatability of the method. The RSD for repeated detection of two different concentrations of CSFV E2 protein samples by different operators at different time points was less than 2%, suggesting good intermediate precision of the method. The peak area of the CSFV E2 protein was linearly related to its concentration, with the regression equation showing R² of 1.000. The LOD and LOQ of the method were 14.88 μg/mL and 29.75 μg/mL, respectively. Application of the developed method in the detection of three batches of CSFV E2 protein antigen and three batches of vaccine demonstrated results consistent with those from the bicinchoninic acid (BCA) assay, which meant that the method could accurately determine the content of CSFV E2 protein antigen and vaccine. The DSF method identified 50 mmol/L Tris-HCl at pH 8.0 as the optimal buffer, and the addition of sugar and alcohol stabilizers further improved the stability of the CSFV E2 protein. The HPSEC method established in this study is simple, fast, and exhibits good accuracy and repeatability, enabling precise measurement of the CSFV E2 protein content. It is expected to play a crucial role in the quality control of the CSFV E2 vaccine. Furthermore, the strategy for improving the CSFV E2 protein stability, identified through DSF screening, has significant implications for enhancing the stability of the CSFV E2 vaccine.
Classical Swine Fever Virus/chemistry* ; Chromatography, Gel/methods* ; Animals ; Swine ; Viral Envelope Proteins/immunology*

Ochratoxin A (OTA) is ubiquitous in the food and feed fields. It has strong hepatotoxicity and nephrotoxicity, seriously threatening the health of humans and animals. Enzymatic degradation of mycotoxins is considered to be a promising method to control mycotoxin contaminations. In this study, a new ochratoxin A amidohydrolase from Microbulbifer thermotolerans (MiADH) was obtained. After heterologous expression in Escherichia coli and purification, the recombinant protein was studied regarding the hydrolysis activity, hydrolysis products, enzymatic properties, and substrate binding mode. MiADH can degrade OTA into ochratoxin α (OTα) and phenylalanine, demonstrating a detoxifying ability. It demonstrated the best performance at 70 ℃ and pH 8.0, and Cu²⁺ had the strongest inhibitory effect on the activity of MiADH. MiADH with good thermal stability exhibited huge potential for industrial application. Rational design guided by three-dimensional structural models and substrate docking analysis revealed the important amino acids affecting substrate binding and obtained multiple mutants with improved activity. Among these mutants, V324A had the highest activity, which was 4.2-fold that of the wild type. The identification of MiADH enriches the ochratoxin A degradation enzyme library and provides a new candidate enzyme for the biological detoxification of ochratoxin A in the food and feed industry.
Amidohydrolases/chemistry* ; Ochratoxins/metabolism* ; Substrate Specificity ; Escherichia coli/metabolism* ; Recombinant Proteins/metabolism* ; Actinomycetales/genetics*

Protein tyrosine phosphatases (PTPs, EC 3.1.3.48) are key regulators of cellular processes, with the catalytic activity attributed to the conserved motif (H/V)CX₅R(S/T), where cysteine and arginine residues are critical. Previous studies revealed that alternative splicing of extracellular phosphatase mRNA precursors in Metarhizium anisopliae generated two distinct transcripts, with the longer sequence containing a novel HCPTPMLS motif resembling PTP signatures but lacking the arginine residue. To identify the novel signature motif and characterize its enzymatic properties, we heterologously expressed and purified both proteins in Pichia pastoris and comprehensively characterized their enzymatic properties. The protein containing the HCPTPMLS motif (designated as L-protein) exhibited the highest activity at pH 5.5 and a strong preference for pTyr substrates. Its phosphatase activity was inhibited by Ag⁺, Zn²⁺, Cu²⁺, molybdate, and tungstate, but enhanced by Ca²⁺ and EDTA. AcP101 (lacking HCPTPMLS) showed the maximal activity at pH 6.5 and a strong preference toward pNPP (P < 0.05), with the activity inhibited by NaF and tartrate, but enhanced by Mg²⁺ and Mn²⁺. Functional analysis confirmed that the L-protein retained the PTP activity despite the absence of arginine in its signature motif, while AcP101 functioned as an acid phosphatase. This study provides the first functional validation of an arginine-deficient PTP motif, expanding the definition of PTP signature motifs and offering new insights for phosphatase classification.
Metarhizium/genetics* ; Protein Tyrosine Phosphatases/chemistry* ; Amino Acid Motifs ; Recombinant Proteins/biosynthesis* ; Amino Acid Sequence ; Pichia/metabolism* ; Fungal Proteins/chemistry* ; Substrate Specificity ; Saccharomycetales

Objective To explore the effect of rehmanniae radix extract(RRE)on chondrocyte apoptosis in the rabbit model of knee osteoarthritis(KOA)by regulating the miR-485-5p/heat shock protein 90 beta family member 1(Hsp90b1)axis.Methods New Zealand rabbits were randomly assigned into control,KOA,low-dose RRE,medium-dose RRE,high-dose RRE,celecoxib,high-dose RRE+antagonist control,and high-dose RRE+miR-485-5p antagonist groups,with 12 rabbits in each group.Rabbits in other groups except the control group were modeled for KOA with the improved Hulth method.After modeling for 8 weeks,the rabbits were administrated with corresponding agents for 4 weeks.The changes in the activity rating of rabbits were recorded.ELISA was employed to measure the levels of tumor necrosis factor-α(TNF-α)and interleukin(IL)-6 in the serum.Safranine O-fast green staining was conducted to reveal the pathological changes in the cartilage tissue and Mankin scoring was performed.TUNEL was employed to detect chondrocyte apoptosis.Real-time fluorescence quantitative PCR was performed to determine the expression of miR-485-5p in the cartilage tissue.Western blot was employed to determine the protein levels of Hsp90b1,cleaved cysteinyl aspartate-specific proteinase-3(Caspase-3),and Bcl2-associated-X(Bax)in the cartilage tissue.The dual-luciferase reporter assay was employed to examine the relationship between miR-485-5p and Hsp90b1.Results Compared with the control group,the KOA group showed down-regulated expression of miR-485-5p,elevated levels of TNF-α and IL-6 in the serum,cartilage erosion and losses,and increases in activity rating,Mankin score,chondrocyte apoptosis rate,and protein levels of Hsp90b1,cleaved Caspase-3,and Bax(all P<0.001).Compared with the KOA group,RRE at low,medium,and high doses,and celecoxib up-regulated the expression of miR-485-5p,lowered the levels of TNF-α and IL-6 in the serum,alleviated the pathological damage to the cartilage tissue,and decreased the activity rating,Mankin score,chondrocyte apoptosis rate,and protein levels of Hsp90b1,cleaved Caspase-3,and Bax(all P<0.05).Compared with the high-dose RRE group and the high-dose RRE+antagonist control group,high-dose RRE+miR-485-5p antagonist down-regulated the expression of miR-485-5p,elevated the levels of TNF-α and IL-6 in the serum,exacerbated the pathological damage to the cartilage tissue,and increased the activity rating,Mankin score,chondrocyte apoptosis rate,and protein levels of Hsp90b1,cleaved Caspase-3,and Bax(all P<0.05).The results indicated that there was a targeted regulatory relationship between miR-485-5p and Hsp90b1.Conclusion RRE may inhibit the expression of Hsp90b1 by up-regulating miR-485-5p,thereby inhibiting chondrocyte apoptosis in the rabbit model of KOA.
Animals ; Rabbits ; Apoptosis/drug effects* ; Chondrocytes/pathology* ; Osteoarthritis, Knee/drug therapy* ; MicroRNAs/metabolism* ; Rehmannia/chemistry* ; Disease Models, Animal ; Tumor Necrosis Factor-alpha/blood* ; Plant Extracts/pharmacology* ; Interleukin-6/blood* ; HSP90 Heat-Shock Proteins/metabolism* ; Male ; Drugs, Chinese Herbal/pharmacology*

OBJECTIVE: To investigate the biological activity and antitumor effect of pegylated recombinant human interleukin 2 (PEG-rhIL-2) obtained by site-specific conjugation of polyethylene glycol (PEG) with non-natural amino acids, and to explore its antitumor mechanism. METHODS: The binding activities of PEG-rhIL-2 at three different sites (T41, Y45, and V91) to human interleukin 2 receptors α (IL-2R_α) and β (IL-2R_β) and were detected by surface plasmon resonance (SPR) technology. Western blot was used to detect the levels of the Janus kinase-signal transducer and activator of transcription 5 (JAK-STAT5) signaling pathway activated by different doses of rhIL-2 and PEG-rhIL-2 in CTTL-2 and YT cells. Blood was collected after a single administration in mice to detect the drug concentration at different time points and evaluate the pharmacokinetic parameters of Y45-PEG-rhIL-2. Mouse hepatoma cell line Hepa1-6, pancreatic cancer cell line Pan-02, and colon cancer cell line MC-38 were selected. Tumor models were constructed in C57BL/6 mice. Different doses of Y45-PEG-rhIL-2 and excipient control were administrated respectively to evaluate the tumor suppression effect of the drug. In the MC-38 colon cancer model, the tumor suppression effect of Y45-PEG-rhIL-2 combined with anti-programmed death-1 (PD-1) monoclonal antibody was evaluated. Hepa1-6 mouse tumor models were constructed and rhIL-2, Y45-rhIL-2 and Y45-PEG-rhIL-2 were administrated respectively. The proportion of tumor-infiltrating lymphocytes was analyzed by flow cytometry. RESULTS: The SPR detection results showed that the binding activities of PEG-rhIL-2 to IL-2R_α/IL-2R_β were both reduced. The affinity of Y45-PEG-rhIL-2 to IL-2R_α was reduced to approximately 1/250, and its affinity to IL-2R_β was reduced to 1/3. Western blot results showed that the activity of Y45-PEG-rhIL-2 in stimulating JAK-STAT5 signaling in CTLL-2 cells expressing heterotrimeric IL-2 receptor complex IL-2R_αβγwas reduced to approximately 1/300, while its activity in YT cells expressing heterodimeric IL-2 receptor complex IL-2R_βγwas reduced to approximately 1/3. The pharmacokinetic evaluation after a single dose in the mice showed that the elimination half-life of Y45-PEG-rhIL-2 was 17.7 h. Y45-PEG-rhIL-2 has pharmacokinetic characteristics superior to those of rhIL-2. Y45-PEG-rhIL-2 showed dose-dependent tumor suppression activity, and the combination of Y45-PEG-rhIL-2 and anti-PD-1 antibody had a better tumor-inhibiting effect than the single use of Y45-PEG-rhIL-2 or anti-PD-1 antibody. Flow cytometry analysis demonstrated that 72 h after the administration of Y45-PEG-rhIL-2, the proportion of tumor-infiltrating cytotoxic T lymphocytes (CD8⁺T cells) increased by 86.84%. At 120 h after administration, the ratio of CD8⁺T cells to regulatory T cells (Treg) increased by 75.10%. CONCLUSION Y45-PEG-rhIL-2 obtained by site-specific conjugation via non-natural amino acids changed its receptor binding activity and inhibited tumor growth in dose-dependent manner in multiple tumor models by regulating CD8⁺T cells.
Interleukin-2/pharmacokinetics* ; Animals ; Mice ; Humans ; Recombinant Proteins/pharmacology* ; Polyethylene Glycols/chemistry* ; Cell Line, Tumor ; Antineoplastic Agents/pharmacokinetics* ; Signal Transduction/drug effects* ; STAT5 Transcription Factor/metabolism* ; Interleukin-2 Receptor alpha Subunit/metabolism* ; Interleukin-2 Receptor beta Subunit/metabolism*