Characterization of an aldo-keto reductase from Thermotoga maritima with high thermostability and a broad substrate spectrum.

A novel aldo-keto reductase gene, Tm1743, from Thermotoga maritima was overexpressed in Escherichia coli. The enzyme displayed the highest activity at 90 °C and at pH 9. It retained 63 % of its activity after 15 h at 85 °C. The enzyme also could tolerate (up to 10 % v/v) acetonitrile, ethanol and 2-propanol with slightly increased activities. Methanol, DMSO and acetone decreased activity slightly. Furthermore, Tm1743 exhibited broad substrate specificity towards various keto esters, ketones and aldehydes, with relative activities ranging from 2 to 460 % compared to the control. Its optimum substrate, 2,2,2-trifluoroacetophenone, was asymmetrically reduced in a coupled NADPH-regeneration system with an enantioselectivity of 99.8 % and a conversion of 98 %.

Biocatalytic characterization of a short-chain alcohol dehydrogenase with broad substrate specificity from thermophilic Carboxydothermus hydrogenoformans.

The gene encoding a novel short-chain alcohol dehydrogenase in the thermophilic bacterium, Carboxydothermus hydrogenoformans, was identified and overexpressed in Escherichia coli. The enzyme was thermally stable and displayed the highest activity at 70 °C and pH 6.0. It preferred NAD(H) over NADP(H) as a cofactor and exhibited broad substrate specificity towards aliphatic ketones, cycloalkanones, aromatic ketones, and ketoesters. Furthermore, ethyl benzoylformate was asymmetrically reduced by the purified enzyme, using an additional coupled NADH regeneration system, with 95 % conversion and in an enantiomeric excess of (99.9 %). The results of this study may lead to the discovery of a novel method for asymmetric reduction of alcohols, which is an important tool in organic synthesis.

Development of a whole-cell biocatalyst with NADPH regeneration system for biosulfoxidation.

A formate dehydrogenase gene (fdh) originated from Candida boidinii was co-expressed in E. coli BL21 (DE3) with the cyclohexanone monooxygenase gene (chmo) cloned from Acinetobacter calcoaceticus NCIMB 9871. The co-expression system was then used as a whole-cell biocatalyst to synthesize chiral phenyl methyl sulfoxide (PMSO) from thioanisole (PMS) and the reaction conditions were investigated. When the initial concentration of PMS was 20 mM, the specific productivity of PMSO in this system was 2.07 µmol g(-1) cw min(-1) (cw: wet cell weight) and the ee value for the R-sulfoxide was 99 %. In contrast, when chmo was the only gene expressed in E. coli, the specific productivity of PMSO was 0.053 µmol g(-1) cw min(-1) with no exact enantioselectivity. Further determination of NADPH concentration in the whole-cell catalysts suggested that co-expression of fdh with chmo significantly improved NADPH supply. Thus, this whole-cell biocatalyst system is highly advantageous for the synthesis of optically pure R-sulfoxide.

Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

To meet more application requirements, improving mechanical properties and self-healing efficiency has become the focus of current research on self-healing PU. The competitive relationship between self-healing ability and mechanical properties cannot be avoided by a single self-healing method. To address this problem, a growing number of studies have combined dynamic covalent bonding with other self-healing methods to construct the PU structure. This review summarizes recent studies on PU materials that combine typical dynamic covalent bonds with other self-healing methods. It mainly includes four parts: hydrogen bonding, metal coordination bonding, nanofillers combined with dynamic covalent bonding and multiple dynamic covalent bond bonding. The advantages and disadvantages of different self-healing methods and their significant role in improving self-healing ability and mechanical properties in PU networks are analyzed. At the same time, the possible challenges and research directions of self-healing PU materials in the future are discussed.

Correction: Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods.

Correction for 'Recent advances in self-healing polyurethane based on dynamic covalent bonds combined with other self-healing methods' by Ze-Wei An et al., Nanoscale, 2023, 15, 6505-6520, https://doi.org/10.1039/D2NR07110J.

Inhibition of MSK1 Promotes Inflammation and Apoptosis and Inhibits Functional Recovery After Spinal Cord Injury.

Mitogen- and stress-activated kinase (MSK) 1 is a nuclear serine/threonine kinase. In the central nervous system, it plays an important role in regulating cell proliferation and neuronal survival; it is also involved in astrocyte inflammation and the inhibition of inflammatory cytokine production. However, its specific role in spinal cord injury is not clear. Here, we aimed to elucidate this role using an in vivo animal model. In this study, we found that MSK1 is gradually decreased, starting 1 day after spinal cord injury and to its lowest level 3 days post-injury, after which it gradually increased. To further investigate the possible function of MSK1 in spinal cord injury, we interfered with its expression by utilizing a small interfering RNA (siRNA)-encoding lentivirus, which was injected into the injured spinal cord to inhibit local expression. After MSK1 inhibition, we found that the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1ß were increased. Moreover, the expression of IL-10 was decreased. In addition, neuronal apoptotic cells were increased significantly and expression of the apoptosis-related protein caspase-3 was also increased. Ultrastructural analysis of nerve cells also revealed typical neuronal apoptosis and severe neuronal damage. Finally, we found that hindlimb motor function decreased significantly with MSK1 knockdown. Therefore, our findings suggest that the inhibition of this protein promotes inflammatory responses and apoptosis and suppresses functional recovery after spinal cord injury. MSK1 might thus play an important role in repair after spinal cord injury by regulating inflammation and apoptosis.