Investigation on the interaction of catalase with sodium lauryl sulfonate and the underlying mechanisms

Novel evidence on iodoacetic acid-induced immune protein functional and conformational changes: Focusing on cellular and molecular aspects

Elevated levels of iodide occur in raw water in certain regions, where iodination disinfection byproducts are formed during chloramine-assisted disinfection of naturally iodide-containing water. Iodoacetic acid (IAA) is one of the typical harmful products. The mechanisms underlying IAA-induced immunotoxicity and its direct effects on biomolecules remained unclear in the past. Cellular, biochemical, and molecular methods were used to investigate the mechanism of IAA-induced immunotoxicity and its binding to lysozyme. In the presence of IAA, the cell viability of coelomocytes was significantly reduced to 70.8 %, as was the intracellular lysozyme activity. Upon binding to IAA, lysozyme underwent structural and conformational changes, causing elongation and unfolding of the protein due to loosening of the backbone and polypeptide chains. IAA effectively quenched the fluorescence of lysozyme and induced a reduction in particle sizes. Molecular docking revealed that the catalytic residue, Glu 35, which is crucial for lysozyme activity, resided within the docking range, suggesting the preferential binding of IAA to the active site of lysozyme. Moreover, electrostatic interaction emerged as the primary driving force behind the interaction between IAA and lysozyme. In conclusion, the structural and conformational changes induced by IAA in lysozyme resulted in impaired immune protein function in coelomocytes, leading to cellular dysfunction.

A Thermostable Lipase Isolated from Brevibacillus thermoruber Strain 7 Degrades Ɛ-Polycaprolactone

The tremendous problem with plastic waste accumulation has determined an interest in biodegradation by effective degraders and their enzymes, such as thermophilic enzymes, which are characterized by high catalytic rates, thermostability, and optimum temperatures close to the melting points of some plastics. In the present work, we report on the ability of a thermophilic lipase, by Brevibacillus thermoruber strain 7, to degrade Ɛ-polycaprolactone (PCL), as well as the enzyme purification, the characterization of its physicochemical properties, the product degradation, and its disruptive effect on the PCL surface. The pure enzyme showed the highest reported optimum temperature at 55 °C and a pH of 7.5, while its half-life at 60 °C was more than five hours. Its substrate specificity referred the enzyme to the subgroup of lipases in the esterase group. A strong inhibitory effect was observed by detergents, inhibitors, and Fe3+ while Ca2+ enhanced its activity. The monomer Ɛ-caprolactone was a main product of the enzyme degradation. Similar elution profiles of the products received after treatment with ultra-concentrate and pure enzyme were observed. The significant changes in PCL appearance comprising the formation of shallower or deeper in-folds were observed after a week of incubation. The valuable enzyme properties of the lipase from Brevibacillus thermoruber strain 7, which caused a comparatively quick degradation of PCL, suggests further possible exploration of the enzyme for effective and environment-friendly degradation of PCL wastes in the area of thermal basins, or in thermophilic remediation processes.

Effects of exposure to anionic surfactants (SDBS and SDS) on nitrogen removal of aerobic denitrifier

In order to explain the effect of anionic surfactants on aerobic denitrification in the urban river, sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfonate (SDS) were added in aerobic denitrifier and the efficiency of nitrogen removal, microbial mechanisms, and enzyme activity was investigated in this study. The results showed that the total nitrogen (TN) and the nitrate nitrogen ( NO 3 - - N ) removal efficiency decreased as an increase of SDBS concentration. In contrast, 59.70% of the TN and 75.12% of NO 3 - - N were removed as the SDBS was 0 mg/L (Control). When SDBS was 200 mg/L (SDBS-200), the removal efficiency of TN and NO 3 - - N was reduced to 4.92% and 4.00%, respectively. However, the denitrification efficiency was significantly accelerated when the concentration of SDS increased, except for 200 mg/L treatment (SDS-200). As the SDS increased from 0 to 100 mg/L (SDS-100), the removal efficiency of TN and NO 3 - - N raised from 59.70% to 70.8% and from 75.12% to 85.08%, respectively. The community structure of aerobic denitrifiers was significantly affected in the SDBS and SDS. While the Cupriavidus and Achromobacter were dominant genera in the group of Control (39.59%, and 42.45%) and SDS-100 (44.40% and 34.86%), the relative abundance of Cupriavidus increased to 84.06% and 59.45% in the group of SDBS-200 and SDS-200, respectively. Enzyme activity assays proved that the nitrite reductase (NiR) relative activity of aerobic denitrification was suppressed by both SDBS and SDS. The increase in the SDS concentrations (from 0 to 50 mg/L) resulted in sharp growth of the nitrate reductase (NR) relative activities (from 100% to 146.86%). These findings demonstrated that SDBS and SDS affected aerobic denitrification efficiency of the aerobic denitrifiers by changing its microbial community structure and enzyme activity. PRACTITIONER POINTS: SDS strengthened aerobic denitrification at low concentration, but the aerobic denitrifiers were inhibited in SDBS. The variation of community structure played a vital role in the aerobic denitrification system. The enzyme activity was seriously affected by SDBS and SDS. Microorganisms and enzyme activity were synergistically involved in the aerobic denitrification.

Investigation of the effect for bisphenol A on oxidative stress in human hepatocytes and its interaction with catalase

Bisphenol A (BPA) as a chemical raw material, is widely used in the manufacturing process of daily necessities. It was reported that BPA could induce oxidative stress, and catalase (CAT) can protect the body from oxidative stress. In this paper, the effect of BPA on CAT was carried out in vitro and in vivo. Firstly, we studied the effects of BPA on oxidative stress, cell viability and CAT activity in human hepatocytes, and the results of vitro experiments show that the survival rate of hepatocytes significant decreased along with the increase of BPA concentration. And when the BPA concentration was 100 μM, the hepatocyte survival decreased by 13.2%, ROS levels in the cells increased by 85%. However, the activity of intracellular CAT increased with the increasing concentration of BPA in 24 h. The results of vivo experiments showed that the activity of CAT in the high-dose group decreased by 29.1% compared with the control group. The long-term effects of BPA on rats reduced the CAT activity in liver, which reduced the resistance to oxidative stress. Meanwhile, the interaction mechanism between BPA and CAT at the molecule level was performed via multiple spectra methods and molecular docking, and the results illustrated that the structural change of CAT is mainly due to the strong combination of BPA with the residues of Trp185. In addition, the interaction mechanism between BPA and CAT were hydrophobic and electrostatic effect. This study provided experimental evidence for better understanding the toxicity of BPA.

Molecular mechanisms of lead-induced changes of selenium status in mice livers through interacting with selenoprotein P

As a heavy metal generally considered to be toxic, lead displays the destruction of the antioxidant system and causes oxidative damage through animal, cellular and molecular evidences. Selenium exists in the form of selenocysteine (Sec) upon its incorporation into selenoproteins and plays vital roles in protection from oxidative stress caused by toxic materials such as lead. This study investigated mechanisms of lead-induced changes of selenium status both at the animal and molecular levels. Total selenium concentrations in blood plasma, contents of glutathione peroxidase 3 (Gpx3) and selenoprotein P (SelP) in blood plasma and mRNA levels of key selenoproteins in mice livers were significantly inhibited after lead exposure, and indicators of oxidative damages in mice livers caused by lead also presented significantly higher, including levels of reactive oxygen species, malonaldehyde concentration and TNF-α levels. To further confirm the hypothesis that lead may disturb selenium status through affecting SelP function, we investigated molecular mechanisms of lead on SelP in vitro. Results indicated that lead changed secondary structure of SelP by loosening and destruction its skeleton. This work presents molecular mechanisms changes of selenium status in mice livers caused by lead combined in vivo and in vitro studies, and contributes to a better understanding of lead toxicity on human health.