Search

[Display omitted] • The basic principle of rational design of electrochemical chiral sensor for sensing is summarized. • Preparation of doped electrodes and their recognition performance for chiral enantiomers are summarized. • Construction of modified electrodes and their recognition performances are discussed. • The challenges and scientific prospects of new generation of modifiers in electrochemical chiral sensing are proposed. Chiral recognition, especially rendering specificity in biomolecular recognition, is a basic property of many biomolecules. Being closely related to the chirality of biomolecules, it has been regarded as one of the most important areas in biological and medical sciences due to the different effects in biological systems. Based on the possible interactions between chiral selectors and the enantiomers, various methods including chromatographic techniques such as gas or liquid chromatography, electromigration techniques such as capillary electrophoresis and so on were developed for the chiral separation and recognition of different optical isomers. Recently, chemical sensors and biosensors have been gradually designed and developed for the analysis of chiral compounds. Based on the difference in electrical response to different isomers, chiral identifications can be successfully implemented. Major successes in enantiomer recognition based on electrochemical analysis are reviewed. The research data available for highly enantio -selective recognition are categorized into several subgroups according to specific topics and critically discussed for the period since 1994, and the latest techniques for electrochemical chiral recognition of enantiomers were also reviewed. Simultaneously, a brief conclusive summary and future perspectives are presented, and the challenges and scientific prospects of the newest generation of electrode modifiers in electrochemical sensing are also proposed. [ABSTRACT FROM AUTHOR]

Highlights • Heterologous promoters could be converted to powerful promoters in S. lividans. • P tac * RBS3 showed stronger capacity for gene expression than the P tipA in S. lividans. • Engineered promoters were also useful for the metabolic engineering of S. lividans. • This study will greatly expand the gene expression toolkit of Streptomyces. Abstract Due to the lack of powerful gene regulation elements, the engineering development of Streptomyces is often limited. Here, we disclosed that the heterologous σ70 -dependent promoters, which have been reported as inefficient tools for gene expression in Streptomyces , could be efficiently recognized by Streptomyces housekeeping factor σ hrdB. Therefore, an effective strategy was developed to engineer these promoters for robust gene expression in Streptomyces by fusing them with optimized 5′-untranslation regions (5′-UTRs). As a proof of concept, the widely used P tac in E. coli was engineered by fusing its core promoter region with the 5′-UTR R15 from a relatively powerful Streptomyces promoter P kasO * R15 and resulted in P tac* , the activity of which was 8.1-fold that of P tac and 1.7-fold that of P kasO * R15 in S. lividans TK24. Next, the 5′-UTR R15 was optimized by randomizing the ribosome binding site (RBS). Based on the base biases of those RBSs with higher activity, eight artificial RBSs were rationally designed, and the optimal resulting promoter P tac * RBS3 showed about 2.1, 3.6, and 17.6 times the activity of P tac *, P kasO * R15 , and P tac , respectively, demonstrating that the heterologous P tac was converted into a type of robust Streptomyces promoters. This study thus greatly expands promoter diversity for the engineering of Streptomyces. [ABSTRACT FROM AUTHOR]