Enantiopure () and () cyclic α,α-disubstituted amino acid derivatives displaying a δ-valerolactam side chain were prepared from a common isoxazolidine precursor. The ()-configured δ-valerolactam was converted into diastereoisomeric pseudopeptides to investigate its ability to induce secondary structures in peptidomimetics. Conformational studies of these pseudopeptides were carried out in the solid state (X-ray diffraction), in solution (NMR analyses), and (computer-aided conformational analysis), which demonstrated that such quaternary amino acids induce β-turn conformations stable enough to be retained in polar media (DMSO). Incorporation of this new type of α,α-disubstituted amino acid into a representative pseudopeptidic sequence by - then -elongation and -debenzylation is also described herein and could serve for the synthesis of various structured peptidomimetics.
The bioluminescence reaction of firefly luciferase with D-luciferin has become an indispensable imaging technique in modern biology and life science experiments, but the high cost of D-luciferin is limiting its further application. Here, we report a practical, one-pot synthesis of D-luciferin from p-benzoquinone (p-BQ), L-cysteine methyl ester and D-cysteine, with an overall yield of 46%. Our route, which is six steps in length and proceeds via 2-cyano-6-hydroxybenzothiazole, is inspired by the mechanistic study of our previously reported biomimetic, non-enzymatic, one-pot formation of L-luciferin from p-BQ and L-cysteine.
Light conversion films are crucial for optimizing vegetable crop production in greenhouses, particularly during winter and spring seasons. This study investigated the effects of a europium-based light conversion film (RPO) compared to traditional polyolefin film (PO film, control) on cucumber (Cucumis sativus L.) cultivation, focusing on handle length, yield, and fruit quality in a randomized complete block design with three replications.
The visible-light-mediated continuous dehydration condensation and oxidative radical dimerization, featuring sulfur hexafluoride (SF) as both a condensation agent and oxidant, have been developed. This photocatalytic method uses commercially available N-protected amino acids as substrates and enables the formation of azlactone monomers and dimers, facilitating efficient utilization and degradation of greenhouse gas SF.
Enzymes are ubiquitous catalysts with enormous application potential in biomedicine, green chemistry, and biotechnology. However, accurately predicting whether a molecule serves as a substrate for a specific enzyme, especially for novel entities, remains a significant challenge. Compared with traditional experimental methods, computational approaches are much more resource-efficient and time-saving, but they often compromise on accuracy.
To explore the effects of the components in the raw materials and by-products of co-pyrolysis on the physicochemical properties of biochar, rice husk （RH, which has a high percentage of lignin and a low content of N） and sawdust （SD, which has a high percentage of both cellulose and N） were used as typical raw materials to prepare co-pyrolysis biochar. The benzene vapor adsorption performance of the obtained biochar was then tested on a fixed-bed device. At the same time, the by-product components generated during pyrolysis were analyzed using thermogravimetric （TG）, scanning electron microscopy （SEM）, and gas chromatography-mass spectrometry （GC-MS）.
