Myosin, a major muscle protein, can be solubilised in a low ionic strength solution containing l -histidine (His). To elucidate which chemical constituents in His are responsible for this solubilisation, we investigated the effects of 5 mM His, imidazole (Imi), l -α-alanine (Ala), 1-methyl- l -histidine (M-his) and l -carnosine (Car) on particle properties of myosin suspensions and conformational characteristics of soluble myosin at low ionic strength (1 mM KCl, pH 7.5). His, Imi and Car, each containing an imidazole ring, were able to induce a myosin suspension, which had small particle size species and high absolute zeta potential, thus increasing the solubility of myosin. His, Imi and Car affected the tertiary structure and decreased the α-helix content of soluble myosin. Therefore, the imidazole ring of His appeared to be the significant chemical constituent in solubilising myosin at low ionic strength solution, presumably by affecting its secondary structure.
Ionic liquids (ILs) as environmental-friendly extractive solvents can remove aromatic heterocyclic sulfur compounds (S-compounds) from fuel oils, which due to their capacity for S-compounds (easy separation and higher selectivity). In this work, a series of polystyrene (PS)-supported polymeric ILs (PS-PILs or PS-6-PILs) with different alkyl side chain length were synthesized. Characterization with Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), elemental analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) demonstrated that IL monomers had been successfully loaded and polymerized on the surface of PS to form a thin polymer coating. The adsorptive desulfurization behavior of polystyrene-supported polymeric ILs was investigated by removing aromatic S-containing compound from model fuel (cyclohexane/thiophene, 2-methylthiophene, benzothiophene, and dibenzothiophene). Under the experimental conditions, the adsorption ability followed the order of PS < PS-PILs < PS-6-PILs. With the length of alkyl chain of imidazole ring increased, the desulfurization rate of thiophene was gradually increased, 2-methylthiophene was first increased and then decreased, benzothiophene and dibenzothiophene were slightly decreased. These trends were due to the different steric effect and aromatic π-electron density of ILs with different alkyl side chain length.
Yukun Zhang,Chong Chen,Changjiang Hu,Jianfeng Zhao,Jun Ma
Photoreduction conversion of soluble U(VI) to insoluble U(IV) is regarded as an ideal strategy for removing uranium from water. The Cyanide-based photocatalysts shows promises for efficient uranium removal but their green synthesis remain significant challenges. Herein, we develop a γ-irradiation-induced strategy for in-situ -CN generation via imidazole ring opening in ZIF-8 MOFs for uranium photoreduction, circumventing the use of toxic cyanide sources. In-situ transmission electron microscopy (TEM) and in-situ X-rays coupled diffraction infrared Fourier transform (DRIFT) reveal morphological evolution via imidazole ring cleavage and -CN formation kinetics during irradiation. Research indicated that -CN-functionalized ZIF-8 displayed superior uranium photoreduction activity through -CN-UO22+ complexation and promotion of photo-induced electron transfer. Impressively, the uranium extraction capacity reached a value of 1532.4 mg/g, higher than most existing MOF-type photocatalysts. In-situ DRIFT spectroscopy revealed the intermediates of the photoreduction uranium reaction and their adsorption mode with the catalyst, providing a comprehensive mechanistic explanation. This work provides a sustainable pathway for uranium photoreduction and guidance for the green design of MOF-type photocatalysts.
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