Melamine ELISA Kit

Osmolytes such as sucrose can interact with the proteins. The aim of the present investigation was to characterize how sucrose could affect the structure, thermal stability and the kinetic of proteinase K. UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, molecular docking, molecular dynamic simulation studies were used to this end. The UV-vis results are represented the intensity enhancement 270 nm due to alteration in the local environment of Tyr and Trp amino acid residues illustrated the tertiary structure changes of proteinase K. The intrinsic fluorescence intensity was decreased regularly with increase the ligand concentration. The secondary structure alterations were revealed an increase in the alpha-helix content of enzyme. The activity of enzyme was increased in the presence of sucrose. Thus, sucrose is an activator for proteinase K. Molecular docking results show a negative value for the Gibbs free energy of the binding confirming the spontaneous proteinase K-sucrose complexation and in agreement with fluorescence results. On the other hand, the thermal stability of proteinase K was investigated in the presence of sucrose. The obtained results show that sucrose led to increment the stability of enzyme in a concentration dependent manner. These results are confirmed by the molecular dynamic simulation technique. (C) 2019 Elsevier B.V. All rights reserved.

Depending on temperature, the 2-amino-2H-[1,2,3]triazolo[4,5-glquinoline-4,9-dione forms two polymorphic structures, which differ in the spatial arrangement of the amine group. Both polymorphs were investigated using different experimental methods as well as various quantum chemical calculations in order to characterise their molecular structures. We used X-ray diffraction, FT-IR and NMR (solid-state and liquid) methods supplemented by the density functional theory (DFF) calculations, molecular electrostatic potential (MEP) and molecular orbital (HOMO, LUMO) analyses. It was found that the arrangement of the amine group affected the crystal structure, formation of H-bonds, the amine and carbonyl vibration bands in the FT-IR spectra, chemical shift of amine group in N-15 CP/MAS NMR and chemical shift of amine protons in H-1 NMR spectra. Both polymorphs were tested on anticancer activity against a panel of human cancer cell lines. Comparing the activity of both compounds showed that activity against MCF-7, MDA-MB-231 and Caco-2 lines depend on the arrangement of the amine group. Moreover, both polymorphs exhibited the highest activity against cell line with high NQO1 protein level, such as: A549, MCF-7 and Caco-2. The molecular docking was used to examine the probable interaction between the ligand of the tested polymorphs and the NQO1 enzyme. The analysis showed that ligands formed a hydrophobic interaction with tryptophan (Trp105), phenylalanine (Phel 26 and Phe178) and tyrosine (Tyr 126). (C) 2020 Elsevier B.V. All rights reserved.