Spermine as a porcine pancreatic elastase activator: spectroscopic and molecular simulation studies.

The aim of this study was to investigate the spermine effect on the thermal denaturation, conformation and activity of elastase at three temperatures of 303, 313 and 323 K in the Tris buffer, at pH 8.5, using UV-vis spectrophotometry, spectrofluorometry and circular dichroism as well as molecular docking and molecular simulation. The increased absorption of elastase in the presence of spermine suggested a change in the environment of tryptophan. It was found that under the influence of spermine, the emission intensity of elastase extremely was reduced, and the use of the Stern-Volmer equation showed that some static quenching had occurred. The thermodynamic parameters values (enthalpy and entropy) and the molecular docking technique also revealed that van der Waals forces or hydrogen bonding interactions played an important role in the binding process. The spermine-elastase complex formation led to increasing the value of the catalytic constant (kcat). So it could be considered as an activator. Slight changes were observed in the second structure of elastase (1.06% increase for the α-helix and 0.048% decrease the ß-sheet) and the thermal stability effect. Molecular docking results also demonstrated that spermine could bind to porcine pancreatic elastase, and van der Waals forces or hydrogen bonding interactions played the major role in the binding process. Overall, our results showed that spermine could induce structural alterations in elastase, acting as a partial stabilizer and an activator for the enzyme.Communicated by Ramaswamy H. Sarma.

Investigating the interaction of porcine pancreatic elastase and propanol: A spectroscopy and molecular simulation study.

The response of porcine pancreatic elastase (PPE) to propanol was examined by various techniques including UV-vis spectrophotometry, spectrofluorometry and circular dichroism, as well as molecular docking and molecular simulation. These techniques were used to investigate the structural changes and elastase activity in the presence of propanol. This work was performed at three temperatures of 303, 313 and 323 K, with the pH value of 8.5 (Tris buffer). The results of the UV-vis spectrophotometry indicated the transfer of tryptophan to an environment with low hydrophobicity. Fluorescence measurements also revealed the quenching of fluorescence intensity was induced by propanol, and dynamic quenching was the proposed quenching mechanism. Kinetic studies also suggested the inhibitory effect (noncompetitive) of propanol on elastase. Further, Circular Dichroism (CD) spectra showed that propanol caused slight alterations in the secondary structures of PPE (0.3% increase for the α-helix and 0.5% decrease for the ß-sheet). Addition of propanol decreased the Tm (Melting Temperature) parameter from 332.8 K to 330.1 K.

A molecular investigation into the interaction of SiO2 nanoparticles with elastase by multispectroscopic techniques and kinetic studies.

The increasing use of nanoparticles in various industries has triggered the need to study their interconnection with biological macromolecules. The goal of this study was to survey the SiO2-nanoparticles efficacy on the thermal denaturation, conformation and activity of elastase at three temperatures of 303, 313 and 323K in the Tris buffer at pH of 8.5. In this work, distinct techniques such as UV-vis Spectrophotometry, Spectrofluorometry, and circular dichroism were employed. The fluorescence studies showed that SiO2 nanoparticles extremely reduced the intensity of elastase with the static mechanism. Thermodynamic parameter analysis also indicated that the process of binding of SiO2-nanoparticles to elastase was spontaneous, thereby suggesting that van der Waals forces or hydrogen bonding interactions played a key role in determining the complex stability. Far-UV circular dichroism studies further revealed that SiO2 nanoparticles could cause 9.79% reduction in the content of the α-helix and 3.24% increase in the content of the ß-sheet. Furthermore, kinetic parameters (Vmax and Kcat/Km) indicated that SiO2 nanoparticles had an activation effect on the elastase activity. Melting temperature studies at the selected concentration of SiO2 nanoparticles also showed that by adding SiO2 nanoparticles, elastase thermal stability was slightly increased. Overall, these nanoparticles modified the structure of the elastase, ultimately changing the activity and stability of this enzyme.

Spectroscopic and molecular docking studies on the interaction between spermidine and pancreatic elastase.

In this study, the impact of spermidine on the stability, conformation and activity of elastase was investigated at the pH of 8.5 (the optimum pH for elastase) and different temperatures (303, 313, and 323 K) using UV-vis spectrophotometry, Spectrofluorimetry, circular dichroism, and enzyme activity measurements. The empirical results were obtained and compared with those achieved by the molecular docking simulation. Spectrofluorometric results proved that with the addition of spermidine to the protein solution, the emission severity of elastase was extremely reduced. Further, the Stern-Volmer equation demonstrated that quenching was principally of the static type. Moreover, ∆H0 and ∆S0 showed a negative value, revealing that hydrogen bonds or van der Waals interactions played a critical role in the interaction between spermidine and elastase. Km and kcat [E] parameters also showed that spermidine acted as an activator for elastase. Far-UV circular dichroism also revealed that spermidine could alter the secondary structure of elastase via a partial increment within the content of the α-helix structure (from 7.8 to 8.6), while it was somewhat diminished in the ß-sheet (from 29.4 to 28.8). Molecular docking simulation results also demonstrated that spermidine could bind to porcine elastase, and van der Waals forces or hydrogen bonding interactions played the main role in this binding. Spermidine, therefore, served as a partial stabilizer and an activator for the enzyme.