Design and Engineering of an Efficient Peroxidase Using Myoglobin for Dye Decolorization and Lignin Bioconversion.

The treatment of environmental pollutants such as synthetic dyes and lignin has received much attention, especially for biotechnological treatments using both native and artificial metalloenzymes. In this study, we designed and engineered an efficient peroxidase using the O2 carrier myoglobin (Mb) as a protein scaffold by four mutations (F43Y/T67R/P88W/F138W), which combines the key structural features of natural peroxidases such as the presence of a conserved His-Arg pair and Tyr/Trp residues close to the heme active center. Kinetic studies revealed that the quadruple mutant exhibits considerably enhanced peroxidase activity, with the catalytic efficiency (kcat/Km) comparable to that of the most efficient natural enzyme, horseradish peroxidase (HRP). Moreover, the designed enzyme can effectively decolorize a variety of synthetic organic dyes and catalyze the bioconversion of lignin, such as Kraft lignin and a model compound, guaiacylglycerol-ß-guaiacyl ether (GGE). As analyzed by HPLC and ESI-MS, we identified several bioconversion products of GGE, as produced via bond cleavage followed by dimerization or trimerization, which illustrates the mechanism for lignin bioconversion. This study indicates that the designed enzyme could be exploited for the decolorization of textile wastewater contaminated with various dyes, as well as for the bioconversion of lignin to produce more value-added products.

Design of Mn-based nanozymes with multiple enzyme-like activities for identification/quantification of glyphosate and green transformation of organophosphorus.

A Mn-based nanozyme, Mn-uNF/Si, with excellent alkali phosphatase-like activity was designed by in-situ growth of ultrathin Mn-MOF on the surface of silicon spheres, and implemented as an effective solid Lewis-Brønsted acid catalyst for broad-spectrum dephosphorylation. H218O-mediated GC-MS studies confirmed the cleavage sites and the involvement of H2O in the new bonds. DRIFT NH3-IR and in-situ ATR-FTIR confirmed the coexistence of Lewis-Brønsted acid sites and the adjustment of adsorption configurations at the interfacial sites. In addition, a green transformation route of "turning waste into treasure" was proposed for the first time ("OPs→PO43-→P food additive") using edible C. reinhardtii as a transfer station. By alkali etching of Mn-uNF/Si, a nanozyme Mn-uNF with laccase-like activity was obtained. Intriguingly, glyphosate exhibits a laccase-like fingerprint-like response (+,-) of Mn-uNF, and a non-enzyme amplified sensor was thus designed, which shows a good linear relationship with Glyp in a wide range of 0.49-750 µM, with a low LOD of 0.61 µM, as well as high selectivity and anti-interference ability under the co-application of phosphate fertilizers and multiple pesticides. This work provides a controllable methodology for the design of bifunctional nanozymes, which sheds light on the highly efficient green transformation of OPs, and paves the way for the selective recognition and quantification of glyphosate. Mechanistically, we also provided deeper insights into the structure-activity relationship at the atomic scale.

Self-compassion and the Mitigation of Negative Affect in the Era of Social Distancing.

OBJECTIVES: The outbreak of contagious diseases and their associated non-pharmaceutical interventions can lead to negative mental health consequences. This study aimed to investigate online self-compassion exercises' effectiveness in alleviating people's negative affect (anxiety and negative emotions) during the COVID-19 pandemic lockdown. METHODS: Study 1 examined the associations between self-compassion and negative affect using an anonymous online survey. In study 2, two pilot experiments were conducted to examine online self-compassion exercises' (i.e., instructor-guided meditation and self-guided writing) effectiveness to mitigate individuals' negative affect. In study 3, a randomized controlled study was conducted to further examine online self-compassion writing's effectiveness in reducing people's negative affect. RESULTS: The results of study 1 indicated a significant negative association between self-compassion and participants' negative affect. Participants in study 2a reported significant decreases in negative affect after completing the self-compassion meditation. Study 2b showed that participants who completed the self-compassion writing reported significantly more self-compassion and less anxiety when compared to participants who did not. Study 3 showed substantial pre/post-test changes in participants who completed self-compassion writing. Importantly, there were significant increases in participants' self-compassion and decreases in negative affect when compared to participants in the control condition. CONCLUSIONS: Self-compassion exercises were effective to alleviate individuals' anxiety and reduce negative emotions (even within a brief session) during the pandemic lockdown. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12671-021-01674-w.