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Two new mixed-ligand copper(ii) complexes, [Cu(PyTA)(l-Phe)Cl]·2H2O (1), [Cu(PyTA)(l-Met)Cl]·0.5H2O (2) (where PyTA = 2,4-diamino-6-(2′-pyridyl)-1,3,5-triazine, l-Phe = l-phenylalanine, l-Met = l-methionine), were synthesized and characterized by elemental analysis, IR, UV-vis, molar conductivity, ESI-MS, and X-ray crystal diffraction. The copper centers of complexes 1 and 2 are in slightly distorted square pyramidal environments, and fluorescence quenching experiments and calorimetry showed that the complexes bound to human serum albumin (HSA) with high affinities (binding constants KD = 3.71 × 106 L mol−1 for 1 and 1.99 × 106 L mol−1 for 2, 1 ＞ 2). UV-vis and circular dichroism (CD) spectroscopic investigations revealed that the complexes induced the alteration of hydrophobic environments and the decrease in the α-helix level of HSA during binding processes. Synchronous fluorescence spectra demonstrated that the binding sites of the complexes on HSA were close to the Trp-214 residue in the IIA subdomain, which was further verified by site marker competitive experiments and the molecular docking method. In vitro cytotoxicity experiments showed that the effective HSA-binding interactions enhanced the cytotoxicity of the complexes. Both 1 and 2 displayed strong anticancer activities against the Eca-109 cell line and induced cell death through the apoptosis pathway. [ABSTRACT FROM AUTHOR]

Immunoassay for pesticides is an emerging analytical method since it is rapid, efficient, sensitive, and inexpensive. In this study, a recombinant antigen-binding fragment (Fab) against a broad set of O,O-diethyl organophosphorus pesticides (DOPs) was produced and characterized. The κ chain and Fd fragment were amplified via PCR and inserted into the vector pComb3XSS and the soluble Fab on phagemid pComb3XSS was induced by isopropyl β-d-thiogalactoside in E. coli TOP 10F’. SDS-PAGE, Western blotting, and indirect competitive ELISA results indicated that Fab maintained the good characteristics of the parental mAb. To better understand antibody recognition, the three-dimensional (3D) model of Fab was built via homologous modeling and the interaction between Fab and DOPs was studied via molecular docking and dynamics simulations. The model clearly explained the interaction manner of Fab and DOPs, and showed that the Arg-L96 and Arg-H52 were mainly responsible for antibody binding. This work provided a foundation for further mutagenesis of Fab to improve its characteristics. [ABSTRACT FROM AUTHOR]

Two new copper(II)-amino acid complexes, [Cu(PyTA)( l -Thr)(ClO 4 )] 2 ·1.5H 2 O ( 1 ) and [Cu(PyTA)( l -Arg)(ClO 4 )(H 2 O)]·ClO 4 ( 2 ) (PyTA = 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine, l -Thr = l -threonine, l -Arg = l -arginine), were successfully synthesized and characterized. The results determined by single crystal X-ray diffraction showed that the five-coordinated copper of 1 and the six-coordinated copper of 2 were located in the distorted square-pyramidal and distorted octahedral environments, respectively. Spectroscopic titrations, thermal denaturation experiments, viscosity measurements revealed that the complexes bound to DNA via a groove binding mode, with the DNA-binding constants of 6.126 × 10 4 M −1 for 1 and 6.464 × 10 4 M −1 for 2 . Electrophoresis experiments revealed that the complexes cleaved pBR322 DNA by an oxidative pathway involving in the generation of superoxide free radical (O 2 − ). Multi-spectroscopic analyses showed that the complexes bound to site I of human serum albumin (HSA) with moderate affinities. In particular, in vitro cytotoxicities of the complexes against Bel-7402 cell line showed promising anticancer effects (IC 50 = 42.1 ± 1.7 μM for 1 ; IC 50 = 36.3 ± 0.9 μM for 2 ). In addition, the binding mechanism and mode of the complexes with DNA/HSA were verified by molecular docking technique. [ABSTRACT FROM AUTHOR]