Radiation-induced inactivation of enzymes – Molecular mechanism based on inactivation of dehydrogenases

Enhancing radiation-resistance and peroxidase-like activity of single-atom copper nanozyme via local coordination manipulation

The inactivation of natural enzymes by radiation poses a great challenge to their applications for radiotherapy. Single-atom nanozymes (SAzymes) with high structural stability under such extreme conditions become a promising candidate for replacing natural enzymes to shrink tumors. Here, we report a CuN3-centered SAzyme (CuN3-SAzyme) that exhibits higher peroxidase-like catalytic activity than a CuN4-centered counterpart, by locally regulating the coordination environment of single copper sites. Density functional theory calculations reveal that the CuN3 active moiety confers optimal H2O2 adsorption and dissociation properties, thus contributing to high enzymatic activity of CuN3-SAzyme. The introduction of X-ray can improve the kinetics of the decomposition of H2O2 by CuN3-SAzyme. Moreover, CuN3-SAzyme is very stable after a total radiation dose of 500 Gy, without significant changes in its geometrical structure or coordination environment, and simultaneously still retains comparable peroxidase-like activity relative to natural enzymes. Finally, this developed CuN3-SAzyme with remarkable radioresistance can be used as an external field-improved therapeutics for enhancing radio-enzymatic therapy in vitro and in vivo. Overall, this study provides a paradigm for developing SAzymes with improved enzymatic activity through local coordination manipulation and high radioresistance over natural enzymes, for example, as sensitizers for cancer therapy.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

The Effect of Dielectric Barrier Discharge Plasma Gas and Plasma-Activated Water on the Physicochemical Changes in Button Mushrooms (Agaricus bisporus)

Button mushrooms (Agaricus bisporus) are highly popular worldwide due to their rich nutritional value and health benefits. However, the rapid water loss rate and browning restrict their economic value. The atmospheric cold plasma (ACP) generated by the plasma equipment used by dielectric barrier discharge preservation technology is widely used for food preservation since it is cost-efficient and environmentally friendly, generating no chemical residues. This study established four treatment groups, namely the direct ACP treatment group (DBD), plasma-activated water immersion group (PAW), pure water immersion group (PW), and control group (control), to explore the effect that ACP preservation technology has on button mushrooms. The results indicated that ACP treatment decreased the pH of pure water from 5.90 ± 0.03 to 5.16 ± 0.03, while significantly increasing the temperature (p < 0.05). During the storage period, the browning index (BI) and E value were the lowest in the PAW group, which exhibited the best hardness and sensory properties. Neither the pH nor water activity changed significantly during the storage period in any of the groups. The polyphenol oxidase (PPO) activity in the button mushroom decreased significantly compared with the control after plasma-activated water treatment. In summary, plasma-activated water significantly reduced the BI and E value of button mushrooms, inhibited PPO activity, and yielded the most stable sensory properties for the optimal preservation of button mushrooms.

Thermal treatment alternatives for enzymes inactivation in fruit juices: Recent breakthroughs and advancements

Fruit juices (FJs) are frequently taken owing to their nutritious benefits, appealing flavour, and vibrant colour. The colours of the FJs are critical indicators of the qualitative features that influence the consumer's attention. Although FJs' intrinsic acidity serves as a barrier to bacterial growth, their enzymatic stability remains an issue for their shelf life. Inactivation of enzymes is critical during FJ processing, and selective inactivation is the primary focus of enzyme inactivation. The merchants, on the other hand, want the FJs to stay stable. The most prevalent technique of processing FJ is by conventional heat treatment, which degrades its nutritive value and appearance. The FJ processing industry has undergone a dramatic transformation from thermal treatments to nonthermal treatments (NTTs) during the past two decades to meet the requirements for microbiological and enzymatic stability. The manufacturers want safe and stable FJs, while buyers want high-quality FJs. According to the past investigation, NTTs have the potential to manufacture microbiologically safe and enzymatically stable FJs with low loss of bioactive components. Furthermore, it has been demonstrated that different NTTs combined with or without other NTTs or mild heating as a hurdle technology increase the synergistic effect for microbiological safety and stability of FJs. Concise information about the variables that affect NTTs' action mode has also been addressed. Primary inactivates enzymes by modifying the protein structure and active site conformation. NTTs may increase enzyme activity depending on the nature of the enzyme contained in FJs, the applied pressure, pH, temperature, and treatment period. This is due to the release of membrane-bound enzymes as well as changes in protein structure and active sites that allow substrate interaction. Additionally, the combination of several NTTs as a hurdle technology, as well as temperature and treatment periods, resulted in increased enzyme inactivation in FJs. Therefore, a combination of thermal and non-thermal technologies is suggested to increase the effectiveness of the process as well as preserve the juice quality.

Recent developments in cold plasma-based enzyme activity (browning, cell wall degradation, and antioxidant) in fruits and vegetables

According to the Food and Agriculture Organization of United Nations reports, approximately half of the total harvested fruits and vegetables vanish before they reach the end consumer due to their perishable nature. Enzymatic browning is one of the most common problems faced by fruit and vegetable processing. The perishability of fruits and vegetables is contributed by the various browning enzymes (polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase) and ripening or cell wall degrading enzyme (pectin methyl-esterase). In contrast, antioxidant enzymes (superoxide dismutase and catalase) assist in reversing the damage caused by reactive oxygen species or free radicals. The cold plasma technique has emerged as a novel, economic, and environmentally friendly approach that reduces the expression of ripening and browning enzymes while increasing the activity of antioxidant enzymes; microorganisms are significantly inhibited, therefore improving the shelf life of fruits and vegetables. This review narrates the mechanism and principle involved in the use of cold plasma technique as a nonthermal agent and its application in impeding the activity of browning and ripening enzymes and increasing the expression of antioxidant enzymes for improving the shelf life and quality of fresh fruits and vegetables and preventing spoilage and pathogenic germs from growing. An overview of hurdles and sustainability advantages of cold plasma technology is presented.

Oxidatively modified glyceraldehyde-3-phosphate dehydrogenase in neurodegenerative processes and the role of low molecular weight compounds in counteracting its aggregation and nuclear translocation

A number of independent studies have shown the contribution of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the pathogenesis of several neurodegenerative disorders. Indeed, GAPDH aggregates have been found in many post-mortem samples of brains of patients diagnosed with Alzheimer's and Parkinson disease. Currently, it is accepted that GAPDH-mediated cell death pathways in the neurodegenerative processes are associated with apoptosis caused by GAPDH nuclear translocation and excessive aggregation under oxidative stress conditions. Also the role of GAPDH in neurodegenerative diseases is linked to it directly binding to specific amyloidogenic proteins and petides such as β-amyloid precursor protein, β-amyloid peptide and tau protein in Alzheimer's disease, huntingtin in Huntington's disease and α-synuclein in Parkinson disease. One of the latest studies indicated that GAPDH aggregates significantly accelerate amyloidogenesis of the β-amyloid peptide, which implies that aggregates of GAPDH may act as a specific aggregation "seed" in vitro. Previous detailed studies revealed that the active-site cysteine (Cys152) of GAPDH plays an essential role in the oxidative stress-induced aggregation of GAPDH associated with cell death. Furthermore, oxidative modification of this cysteine residue initiates the translocation of the enzyme to the nucleus, subsequently leading to apoptosis. The crystallographic structure of GAPDH shows that the Cys152 residue is located close to the surface of the molecule in a hydrophilic environment, which means that it can react with low molecular weight compounds such as hydroxynonenal or piceatannol. Therefore, it is highly possible that GAPDH may serve as a target for small molecule compounds with the potential to slow down or prevent the progression of neurodegenerative disorders. Recently appearing new evidence has highlighted the significance of low molecular weight compounds in counteracting the oxidation of GAPDH and consequently its aggregation and other unfavourable pathological processes. Hence, this review aims to present all recent findings concerning molecules that are able to interact with GAPDH and counteract its aggregation and translocation to the nucleus.

Functional consequences of piceatannol binding to glyceraldehyde-3-phosphate dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is one of the key redox-sensitive proteins whose activity is largely affected by oxidative modifications at its highly reactive cysteine residue in the enzyme’s active site (Cys149). Prolonged exposure to oxidative stress may cause, inter alia, the formation of intermolecular disulfide bonds leading to accumulation of GAPDH aggregates and ultimately to cell death. Recently these anomalies have been linked with the pathogenesis of Alzheimer’s disease. Novel evidences indicate that low molecular compounds may be effective inhibitors potentially preventing the GAPDH translocation to the nucleus, and inhibiting or slowing down its aggregation and oligomerization. Therefore, we decided to establish the ability of naturally occurring compound, piceatannol, to interact with GAPDH and to reveal its effect on functional properties and selected parameters of the dehydrogenase structure. The obtained data revealed that piceatannol binds to GAPDH. The ITC analysis indicated that one molecule of the tetrameric enzyme may bind up to 8 molecules of polyphenol (7.3 ± 0.9). Potential binding sites of piceatannol to the GAPDH molecule were analyzed using the Ligand Fit algorithm. Conducted analysis detected 11 ligand binding positions. We indicated that piceatannol decreases GAPDH activity. Detailed analysis allowed us to presume that this effect is due to piceatannol ability to assemble a covalent binding with nucleophilic cysteine residue (Cys149) which is directly involved in the catalytic reaction. Consequently, our studies strongly indicate that piceatannol would be an exceptional inhibitor thanks to its ability to break the aforementioned pathologic disulfide linkage, and therefore to inhibit GAPDH aggregation. We demonstrated that by binding with GAPDH piceatannol blocks cysteine residue and counteracts its oxidative modifications, that induce oligomerization and GAPDH aggregation.