Structural change of myoglobin structure after binding with spermidine

Effect mechanism of capsaicin and dihydrocapsaicin in chili on the oxidative stability of myoglobin in duck meat

BACKGROUND

Myoglobin (Mb) in duck meat is commonly over-oxidized when heated at high temperatures, which may worsen the color of the meat. Enhancing the oxidative stability of Mb is essential for improving the color of duck meat. Capsaicin and dihydrocapsaicin (CA-DI) in chili exhibit antioxidant properties. This study investigated the effects of CA-DI on the structure and oxidative damage of Mb by fluorescence spectroscopy, differential scanning calorimetry analysis and particle size in duck meat during heat treatment.

RESULTS

When the ratio of CA-DI to Mb was 10:1 g kg-1 and heat-treated for 36 min, oxymyoglobin significantly increased, and metmyoglobin significantly decreased compared with the control group (P < 0.05). In parallel, the carbonyl content of Mb in the CA-DI group decreased by 43.40 ± 0.10%, the sulfhydryl content increased by 188 ± 0.21%, and the free radical scavenging activity of Mb was significantly enhanced (P < 0.05). Moreover, the addition of CA-DI resulted in a significant decrease in the particle size of the Mb surface (P < 0.05). When the ratio of CA-DI to Mb was 10:1 g kg-1, CA-DI enhanced the thermal stability and significantly increased the thermal denaturation temperature of Mb. The molecular docking results indicated that hydrophobic interactions and hydrogen bonds were involved in the binding of CA-DI to Mb.

CONCLUSION

CA-DI could combine with Mb and improve the oxidation stability of Mb in duck meat. This suggested that CA-DI could be a potential natural antioxidant that improves the color of meat products. © 2024 Society of Chemical Industry.

Thermodynamic and functional changes of alpha-chymotrypsin after interaction with gallic acid

In the present study, the interaction mechanism between gallic acid (GA) and α-Chymotrypsin (α-CT) was investigated by employing a series ofspectroscopic methods, computational docking and molecular dynamic (MD) simulation. Fluorescence spectra analysis indicated the formation of a stable complex between GA and α-CT, where the quenching of the fluorescence emission was predominantly characterized by a static mechanism. TheCA obtained binding constants for the α-CT-GA complex were in the order of 103 M-1, indicating the moderate binding affinity of GA for α-CT. The corresponding CD findings showed that the interaction between GA and α-CT resulted in an alteration of the protein's secondary structure. The findings of the enzyme activity investigation clearly showed that the presence of GA led to a notable decline in the enzymatic activity of α-CT, highlighting GA's function as an effective inhibitor for α-CT. The molecular docking simulations revealed the optimal binding site for the GA molecule within the α-CT structure and MD simulations confirmed the stability of the α-CT-GA complex. This research expands our comprehension regarding the behavior of enzymes in the presence of small-molecule ligands and opens avenues for food safety.

Interaction between the antioxidant compound safranal and α-chymotrypsin in spectroscopic fields and molecular modeling approaches

Among various herbal plants, saffron has been the subject of study in various medical and food fields. Among the compounds of saffron, safranal is one of them. Safranal is a monoterpene aldehyde. The precursor of safranal is called picrocrocin, whose hydrolysis leads to the production of safranal. picrocrocin has two sugar components and aglycone. sugar component was separated during the drying process of saffron and safranal is produced. Saffron is the cause of the saffron aroma. Previous studies have shown that safranal offers many benefits such as antioxidants, blood pressure regulation and anti-tumor qualities. On the other hand, α-Chy is an enzyme secreted by the pancreas into the intestine and then acts as an efficient protease. In this study, various methods, such as molecular dynamics (MD) simulation and molecular binding, and different spectroscopic techniques, as well as protein stability techniques, were used to investigate the possible interactions between safranal and α-Chy. UV spectroscopic studies were showing that the existence of safranal decreased α-Chy absorption intensity. safranal caused the intrinsic fluorescence of α-Chy to be quenched too. According to the Stern-Volmer equation, the interaction between safranal and α-Chy was of the static type. In thermodynamic calculations, the interaction between safranal and α-Chy was stabilized by hydrophobic forces. And it was found that this interaction continued spontaneously. These results were, thus, consistent with the Docking data simulation (with the negative ΔG° number and positive changes in enthalpy and entropy). The thermal stability of α-Chy was also measured, showing that its melting point was shifted to a higher threshold as a result of the interaction. also, MD simulation indicated that α-Chy became more stable in the presence of safranal. In this paper, all the results of the laboratory techniques were confirmed by molecular dynamic simulations, so the correctness of the results was confirmed. From this research, we hope to carefully observe the possible changes in the behavior and structure of the enzyme in the presence of safranal.Communicated by Ramaswamy H. Sarma.

Investigating the effect of pH on the interaction of cypermethrin with human serum albumin: Insights from spectroscopic and molecular dynamics simulation studies

To efficiently combat the negative consequences of the utilization of pesticides and hazardous substances with biomolecules, it is crucial to comprehend the features of the corresponding compounds. In this study, interactions between cypermethrin (CYP) and HSA at neutral and acidic pH were investigated using a set of spectroscopic and computational tools, such as UV/VIS's absorption spectroscopy, fluorescence, Fourier-transform infrared (FTIR) spectroscopy, molecular docking, and molecular dynamics. Furthermore, the effect of CYP on the HSA thermal stability was investigated. The increase in the CYP concentration at acidic and neutral pH resulted in static HSA fluorescence quenching. In the interaction between HSA and CYP at both pH, increasing the temperature led to a decrease in the Stern-Volmer quenching constant and the binding constant. We also revealed that with increasing CYP concentration, the melting temperature of HSA increases at both pH values.

Evidence for paraquat-pepsin interaction: In vitro and silico study

The use of the herbicide paraquat (PQ) has raised concerns about potential environmental consequences due to its toxicity and persistence in the environment. Considering the affinity of dangerous compounds to biological molecules, it is necessary to know their binding properties. This article focuses on the behavior of the pepsin enzyme following its contact with paraquat poison, and the interaction between paraquat and pepsin has been investigated in laboratory conditions and simulated physiological conditions using multispectral techniques. Fluorescence experiments showed that PQ uses a static method to quench pepsin's intrinsic fluorescence. By causing structural damage to pepsin, PQ may be detrimental as it alters its conformational function based on FT-IR spectroscopy. The coupling reaction is a spontaneous process caused by hydrogen bonding and van der Waals forces according to the analysis of the thermodynamic parameters of each system at three different temperatures. The molecular structure of pepsin changes when it binds to PQ. Also, the results showed that PQ is a pepsin inhibitor that changes the function of the enzyme.

Change in thermal stability and molecular structure characteristics of whey protein beta-lactoglobulin upon the interaction with levamisole hydrochloride

The interaction between beta-lactoglobulin (BLG) and anthelmintic compounds including levamisole (LEV) is a matter of great concern as it not only poses potential health and environmental risks but also has significant implications for food processing and production. The mechanisms of LEV-BLG interaction were investigated through spectral and molecular modeling approaches. Fluorescence and UV-Visible investigations indicated the formation of a spontaneous and stable LEV-BLG complex. Structural changes of BLG were revealed by circular dichroism and Fourier transform infrared studies. The thermal stability of BLG increased in the presence of LEV. Molecular docking studies indicated the best mode of LEV-BLG interaction and molecular dynamics simulation confirmed the stability of the LEV-BLG complex. In conclusion, our study sheds light on the potential of BLG to interact with deleterious substances such as anthelmintic agents, thus highlighting the necessity of further research in this field to assure food safety and prevent any health hazards.

Structural alterations and inhibition of lysozyme activity upon binding interaction with rotenone: Insights from spectroscopic investigations and molecular dynamics simulation

The pervasive employment of pesticides such as rotenone on a global scale represents a substantial hazard to human health through direct exposure. Therefore, exploring the interactions between such compounds and body macromolecules such as proteins is crucial in comprehending the underlying mechanisms of their detrimental effects. The present study aims to delve into the molecular interaction between rotenone and lysozyme by employing spectroscopic techniques along with Molecular dynamics (MD) simulation in mimicked physiological conditions. The binding interaction resulted in a fluorescence quenching characterized by both dynamic and static mechanisms, with static quenching playing a prominent role in governing this phenomenon. The analysis of thermodynamic parameters indicated that hydrophobic interactions primarily governed the spontaneous bonding process. FT-IR and circular dichroism findings revealed structural alternations of lysozyme upon complexation with rotenone. Also, complexation with rotenone declined the biological activity of lysozyme, thus rotenone could be considered an enzyme inhibitor. Further, the binding interaction substantially decreased the thermal stability of lysozyme. Molecular docking studies showed the binding location and the key residues interacting with rotenone. The findings of the spectroscopic investigations were confirmed and accurately supported by MD simulation studies.

Research advances of molecular docking and molecular dynamic simulation in recognizing interaction between muscle proteins and exogenous additives

During storage and processing, muscle proteins, e.g. myosin and myoglobin, will inevitably undergo degeneration, which is thus accompanied by quality deterioration of muscle foods. Some exogenous additives have been widely used to interact with muscle proteins to stabilize the quality of muscle foods. Molecular docking and molecular dynamics simulation (MDS) are regarded as promising tools for recognizing dynamic molecular information at atomic level. Molecular docking and MDS can explore chemical bonds, specific binding sites, spatial structure changes, and binding energy between additives and muscle proteins. Development and workflow of molecular docking and MDS are systematically summarized in this review. Roles of molecular simulations are, for the first time, comprehensively discussed in recognizing the interaction details between muscle proteins and exogenous additives aimed for stabilizing color, texture, flavor, and other properties of muscle foods. Finally, research directions of molecular docking and MDS for improving the qualities of muscle foods are discussed.