ABSTRACT
Engineered protein switches have been widely applied in cell-based protein sensors and point-of-care diagnosis for the rapid and simple analysis of a wide variety of proteins, metabolites, nucleic acids, and enzymatic activities. Currently, these protein switches are based on two main types of switching mechanisms to transduce the target binding event to a quantitative signal, through a change in the optical properties of fluorescent molecules and the activation of enzymatic activities. In this paper, we introduce a new affinity-tunable protein switch strategy in which the binding of a small-molecule target with the protein activates the streptavidin-biotin interaction to generate a readout signal. In the absence of a target, the biotinylated protein switch forms a closed conformation where the biotin is positioned in close proximity to the protein, imposing a large steric hindrance to prevent the effective binding with streptavidin. In the presence of the target molecule, this steric hindrance is removed, thereby exposing the biotin for streptavidin binding to produce strong fluorescent signals. With this modular sensing concept, various sulfonamide, methotrexate, and trimethoprim drugs can be selectively detected on the cell surface of native and genetically engineered cells using different fluorescent dyes and detection techniques.
Subject(s)
Biotin , Nucleic Acids , Biotin/chemistry , Fluorescent Dyes , Methotrexate , Proteins , Streptavidin/analysis , Sulfonamides , TrimethoprimABSTRACT
We report an efficient and mild tandem catalytic process for the synthesis of functionalized pyrrole-3-carbaldehydes. These compounds were obtained by a one-pot three-component reaction of 5-bromo-1,2,3-triazine, terminal alkynes, and primary amines via a palladium-catalyzed Sonogashira coupling reaction, and then annulation through a silver-mediated reaction of the resulting alkynyl 1,2,3-triazines allowed for access to the multifunctionalized pyrrole-3-carbaldehydes.
ABSTRACT
A regioselective C-H sulfanylation of aryl sulfoxides with alkyl aryl sulfides in the presence of acid anhydride was developed, which resulted in the formation of 1,4-disulfanylarenes after dealkylation of initially formed sulfonium salts. The reaction began with Pummerer-type activation of aryl sulfoxides followed by nucleophilic attack of alkyl aryl sulfides. The nucleophilic attack occurred exclusively at the para positions, or at specific positions in case the para position was not available, under perfect control by the dominating sulfoxide directors regardless of any other substituents. The initially formed aryl sulfonium salts were isolable and usefully served as aryl halide surrogates for palladium-catalyzed arylation with sodium tetraarylborates.
ABSTRACT
OBJECTIVE: Genetic variation of cadheri23 (cdh23; 753G>A in exon 7) has been implicated with age-related hearing impairment (ARHI) in mice. This study aimed to test the association of the CDH23 tag single nucleotide polymorphism (SNP) in intron 7 with ARHI in Han Chinese. STUDY DESIGN: Individual cohort study. SETTING: Tertiary medical center. SUBJECTS AND METHODS: A total of 1175 Han Chinese subjects were divided into the case group (n = 310, 26% with poorest hearing) and the control group (n = 308, the 26% with best hearing) according to the Z(high) score converted from the original frequency-specific hearing thresholds. The CDH23 SNP locus (rs7087735: C/T) in intron 7 (coordinate: 72996763) shown in the HapMap was genotyped with correlation to the hearing phenotype. RESULTS: The genotype distributions of CDH23 (CC/CT/TT) were not significantly different between the case and control group (P = .489). Compared with genotype CC, the odds ratios of the genotypes CT and TT for ARHI were not significantly different after adjustment for other environmental factors (P = .299 for CT; P = .610 for TT). CONCLUSIONS: Despite that the Ahl allele of Cdh23 had been implicated with ARHI in mice, we found no positive association of the CDH23 tag SNP in intron 7 with ARHI in Han Chinese.
