RESUMO
Since imine reductases (IREDs) were reported to catalyze the reductive amination reactions, they became particularly attractive for producing chiral amines. Though diverse ketones and aldehydes have been proved to be excellent substrates of IREDs, bulky amines have been rarely transformed. Here we report the usage of an Increasing-Molecule-Volume-Screening to identify a group of IREDs (IR-G02, 21, and 35) competent for accepting bulky amine substrates. IR-G02 shows an excellent substrate scope, which is applied to synthesize over 135 amine molecules as well as a range of APIs' substructures. The crystal structure of IR-G02 reveals the determinants for altering the substrate preference. Finally, we demonstrate a gram-scale synthesis of an analogue of the API sensipar via a kinetic resolution approach, which displays ee >99%, total turnover numbers of up to 2087, and space time yield up to 18.10 g L-1 d-1.
RESUMO
Although zinc oxide nanoparticles are known as an effective antimicrobial agent, the mechanism for its antifungal activity has been assessed by only few studies. In this study, antifungal activity mechanism for ZnO via the change of physiology was explored. It was showed that the activities of SOD and CAT and the MDA content were increased significantly. The possible mechanisms were obtained that zinc oxide directly acts on the mycelium of penicillium to produce oxidative stress and destroy intracellular physiological balance. RNA-seq was then used to verify the conclusion obtained before, and obtained results suggested that the antifungal mechanism is attributed to oxidative stress and changes in membrane function.
