Purification and characterization of thermostable superoxide dismutase from Anoxybacillus gonensis KA 55 MTCC 12684

Novel flavonol derivatives containing benzoxazole as potential antiviral agents: design, synthesis, and biological evaluation

A series of flavonol derivatives containing benzoxazole were designed and synthesized, and the structures of all the target compounds were determined by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). The structure of X2 was further confirmed by single crystal X-ray diffraction analysis. The results of the bioactivity tests showed that some of the target compounds possessed excellent antiviral activity against tobacco mosaic virus (TMV) in vivo. In particular, the median effective concentration (EC50) values for the curative and protective activities of X17 against TMV were 127.6 and 101.2 μg/mL, respectively, which were superior to those of ningnanmycin (320.0 and 234.6 μg/mL). The results of preliminary mechanism study indicated that X17 had a strong binding affinity for TMV coat protein (TMV-CP), which might hinder the self-assembly and replication of TMV particles. In addition, X17 was able to effectively inhibit tobacco leaf membrane lipid peroxidation and facilitate the removal of O2- from the body, thereby improving the disease resistance of tobacco plants. Therefore, the design and synthesis of flavonol derivatives containing benzoxazole provides value for the development of new antiviral drugs.

A novel highly thermostable and stress resistant ROS scavenging metalloprotein from Paenibacillus

Reactive oxygen species (ROS) are unstable metabolites produced during cellular respiration that can cause extensive damage to the body. Here we report a unique structural metalloprotein called RSAPp for the first time, which exhibits robust ROS-scavenging activity, high thermostability, and stress resistance. RSAPp is a previously uncharacterized DUF2935 (domain of unknown function, accession number: cl12705) family protein from Paenibacillus, containing a highly conserved four-helix bundle with binding sites for variable-valence metal ions (Mn2+/Fe2+/Zn2+). Enzymatic characterization results indicated that RSAPp displays the functionality of three different antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). In particular, RSAPp exhibits a significant SOD-like activity that is remarkably effective in eliminating superoxide radicals (up to kcat/KM = 2.27 × 1011 mol-1 s-1), and maintains the catalytical active in a wide range of temperatures (25-100 °C) and pH (pH 2.0-9.0), as well as resistant to high temperature, alkali and acidic pH, and 55 different concentrations of detergent agents, chemical solvents, and inhibitors. These properties make RSAPp an attractive candidate for various industrial applications, including cosmetics, food, and pharmaceuticals.

Finding and engineering the newly found bacterial superoxide dismutase enzyme to increase its thermostability and decrease the immunogenicity: a computational and experimental research

Superoxide dismutase (SOD) is one of the most important antioxidant enzymes that can reduce oxidative stress in the cell environment. Nowadays, bacterial sources of enzyme are commercially applicable in the cosmetics and pharmaceutical industries, but the allergenic effect of proteins from non-human sources has been mentioned as disadvantage of these kinds of enzymes. In this study, to find the suitable bacterial SOD candidate for decreasing immunogenicity, the sequences of five thermophilic bacteria were selected as reference species. Then, linear and conformational B-cell epitopes of the SOD were analyzed by different servers. The stability and immunogenicity of mutant positions were also evaluated. The mutant gene was inserted into the pET-23a expression vector and transformed into E. Coli BL21 (DE3) for expression of the recombinant enzyme. Afterward, the expression of the mutant enzyme was evaluated by SDS-PAGE analysis and the recombinant enzyme activity was assessed. Anoxybacillus gonensis was selected as a reasonable SOD source according to BLAST search, physicochemical properties analysis, and prediction of allergenic features. Regarding our results, five residues including E84, E142, K144, G147, and M148 were predicted as candidates for mutagenesis. Finally, the K144A was chosen as the final modification due to the increase in the stability of the enzyme and decreased immunogenicity of the enzyme as well. The enzyme activity was 240 U/ml at room temperature. Alternation in K144 to alanine caused increased stability of the enzyme. In silico studies confirmed non-antigenic protein after mutation.

Design, Synthesis, and Bioactivity of Chalcone Derivatives Containing Indanone

A series of chalcone derivatives containing indanone were designed and synthesized by aldehyde-ketone condensation and etherification. The activity test demonstrated that the majority of the compounds had good therapeutic and protective activities against tobacco mosaic virus (TMV) at a concentration of 500 μg/mL when being tested. Among them, the target compounds N2 and N7 showed good therapeutic activities against TMV with EC₅₀ values of 70.7 and 89.9 μg/mL, respectively, which were better than that of ningnanmycin (158.3 μg/mL). N2 and N10 showed better protective activities against TMV with EC₅₀ values of 60.8 and 120.3 μg/mL, which were superior to that of ningnanmycin (175.6 μg/mL). A hydrogen bond interaction was observed between N2 and ARG-341 with a bond length of 3.08 Å and a hydrogen bond was observed between ningnanmycin and ASP-66 with a bond length of 3.72 Å. In contrast, the hydrogen bond length of compound N2 was shorter and its binding was closer. Meanwhile, when the heartleaf tobacco was being treated with N2, its increasing rate of malondialdehyde slowed and its content of defense enzymes significantly increased, again reflecting the good activity of N2 against TMV.

Production of a Novel Superoxide Dismutase by Escherichia coli and Pichia pastoris and Analysis of the Thermal Stability of the Enzyme

Previously, a new copper-zinc SOD (CuZnSOD) isolated from chestnut rose (Rosa roxburghii) with good stability was described. In this study, the biosynthetic approach was used to create recombinant CuZnSOD. RACE PCR was also used to amplify the full-length CuZnSOD gene from chestnut rose, and the ORF segment was expressed in E. coli BL21 and P. pastoris GS115. For characterization, the enzyme was isolated in two steps in E. coli and one step in P. pastoris. The biochemical properties of the two recombinant enzymes were similar, and their optimal reaction pH and temperature were 6.0 and 50°C, respectively. According to molecular dynamics simulation, the CuZnSOD showed high stability from 70 to 90°C, and eight amino acids are important for enzyme thermal stability at high temperatures. This study set the stage for industrial manufacture by filling gaps in the link between conformational changes and the thermal stability of the new CuZnSOD.

Nanocarriers-based immobilization of enzymes for industrial application

Nanocarriers-based immobilization strategies are a novel concept in the enhancement of enzyme stability, shelf life and efficiency. A wide range of natural and artificial supports have been assessed for their efficacy in enzyme immobilization. Nanomaterials epitomize unique and fascinating matrices for enzyme immobilization. These structures include carbon nanotubes, superparamagnetic nanoparticles and nanofibers. These nano-based supports offer stable attachment of enzymes, thus ensuring their reusability in diverse industrial applications. This review attempts to encompass recent developments in the critical role played by nanotechnology towards the improvement of the practical applicability of microbial enzymes. Nanoparticles are increasingly being used in combination with various polymers to facilitate enzyme immobilization. These endeavors are proving to be conducive for enzyme-catalyzed industrial operations. In recent years the diversity of nanomaterials has grown tremendously, thus offering endless opportunities in the form of novel combinations for various biotransformation experimentations. These nanocarriers are advantageous for both free enzymes and whole-cell immobilization, thus demonstrating to be relatively effective in several fermentation procedures.

A thermostable Fe/Mn SOD of Geobacillus sp. PCH100 isolated from glacial soil of Indian trans-Himalaya exhibits activity in the presence of common inhibitors

Superoxide dismutases are the enzymes involved in dismutation of superoxide radicals into oxygen and hydrogen peroxide. The present work reports a thermostable Fe/Mn SOD of Geobacillus sp. strain PCH100 (GsSOD) isolated from glacial soil. Purified recombinant GsSOD is a dimeric protein of ~57 kDa that exhibited highest activity at a temperature of 10 °C and pH of 7.8. Maximum enzyme velocity and Michaelis constant of the GsSOD were 1098.90 units/mg and 0.62 μM, respectively. At 80 °C, thermal inactivation rate constant and half-life of GsSOD were 3.33 × 10^-3 min^-1 and 208 min, respectively. Interestingly, GsSOD tolerated a temperature of 100 °C and 130 °C up to 15 min and 5 min, respectively. Circular dichroism and differential scanning calorimetry confirmed thermostable nature of GsSOD. Apoenzyme of GsSOD regained enzymatic activity in the presence of Fe²⁺ and Mn²⁺ as metal ion cofactors. GsSOD was stable under varying concentrations of chemicals, namely ethylenediaminetetraacetic acid, potassium cyanide, hydrogen peroxide, chloroform-ethanol, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate, Tween-20, Triton X-100, urea, and guanidine hydrochloride. The enzyme exhibited >70% activity in presence of 10 mM metal ions. Owing to its thermostable nature and resistance to chemical inhibitors, GsSOD is a potential enzyme for industrial applications.

Nitrile hydratase mediated green synthesis of lactamide by immobilizing Rhodococcus pyridinivorans NIT-36 cells on N, N'-Methylene bis-acrylamide activated chitosan

In this paper green synthesis of an important commodity chemical lactamide has been undertaken using chitosan immobilized Rhodococcus pyridinivorans NIT-36 harbouring nitrile hydratase (NHase) enzyme. The cells immobilization (300 mg/g) is based on the partial entrapment of cells by suspension cross-linking technique facilitated by N, N'-Methylene bis-acrylamide. In the repeated-use experiments, the immobilized cells retained 80% of its initial activity when stored at 4 °C for 30 days. NHase activity of free and immobilized cells was studied over temperature ranging from 25 °C to 60 °C. The activity for free cells showed a sharp decline of 70% when the reaction temperature was elevated from 45 °C to 50 °C whereas chitosan immobilized cells retained their activity in the same temperature range. A fed-batch reaction was designed and the immobilized cells showed 100% similar enzymatic pattern for five consecutive rounds which gradually decreased in following cycles. A volumetric productivity of 20 g/L and catalytic productivity of 8.33 g/g dcw/h for lactamide were achieved.

Juglans regia and Ribes nigrum as potential nutraceuticals: Source of thermostable superoxide dismutase enzyme

In the present study, superoxide dismutase (SOD) extracted from dry fruits; Juglans regia (Walnut; W) and Ribes nigrum (Munakka; M) was partially purified into 0%-40% and 40%-80% fractions based on ammonium sulfate saturation levels. The partially purified fractions (0%-40%) exhibited purification level of 3.09- (W) and 3.22- (M) fold with specific activity 79.32 Umg^-1 (W) and 125.23 Umg^-1 (M). SOD from both the sources was found to be thermally stable, that is, 80°C (W) and 70°C (M). Kinetic studies showed K_m values to be 3.33 mM (W) and 2.86 mM (M), whereas the activation energy (E_a ) calculated as 24.52 KJ mol^-1 (W) and 26.25 KJ mol^-1 (M). Na⁺ , Mn²⁺ , and Ba²⁺ ions acted as potential inhibitors, whereas Fe²⁺ stimulated SOD from both the sources. Among these metal ions, Na⁺ exhibited uncompetitive inhibition in both cases; with K_i values of 0.7 mM (W) and 0.9 mM (M), suggesting the more prominent binding affinity and effectiveness. PRACTICAL APPLICATIONS: Awareness need to be created among people for multifactorial health benefits of nutraceuticals in day-to-day life. Nutritional consumption from fruits, nuts, and vegetables safeguard against various maladies like cardiovascular diseases, diabetes, and cancers. Superoxide dismutase (EC 1.15.1.1) is a standout among the most critical metal-containing enzymes that act as a main line of defense against oxidative stress. Antioxidant-based drugs and formulations have been developed in the recent years and research is emphasized on its impact on oxidative stress levels. In this study, Juglans regia (W) and Ribes nigrum (M) were found to have thermostable SOD enzyme with excellent antioxidant properties. Thermal stability of an enzyme improves its significance making it industry friendly with therapeutically vital products, alongside their utilization as supplement in numerous therapeutic formulations.

Enhanced stability of manganese superoxide dismutase by amino acid replacement designed via molecular dynamics simulation

In order to improve manganese-SOD stability, three mutations were constructed via site-directed mutagenesis, and the root mean square fluctuation (RMSF) and root mean square deviation (RMSD) were used as stability assessment indexes. The amino acids of V140, E155 and E215 from wild-type mouse Mn-SOD was replaced to L140, W155 and W215, and a recombinant plasmid containing DNA segment coding wild-type and mutant Mn-SOD protein was transformed into Escherichia coli BL21 for expression. The highest enzyme activity of the mutations-MnSOD was 2050 U/mg. In addition, the recombinant protein, TM-MnSOD^{V140L, E155W, E215W} exhibited higher working temperature and improved stability compared with the wild-type Mn-SOD. Furthermore, CD spectrum analysis of the improved mutants and wild-type enzyme showed that there was no significant change in their secondary structures. This study not only expands the scope of the application of enzymes, but also helps us understand the relationship between protein structure and function.