Structural basis to characterise transactivation domain of BRCA1

Mobile Loop in the Active Site of Metallocarboxypeptidases as an Underestimated Determinant of Substrate Specificity

It is generally accepted that the primary specificity of metallocarboxypeptidases is mainly determined by the structure of the so-called primary specificity pocket. However, the G215S/A251G/T257A/D260G/T262D mutant of carboxypeptidase T from Thermoactinomyces vulgaris (CPT) with the primary specificity pocket fully reproducing the one in pancreatic carboxypeptidase B (CPB) retained the broad, mainly hydrophobic substrate specificity of the wild-type enzyme. In order to elucidate factors affecting substrate specificity of metallocarboxypeptidases and the reasons for the discrepancy with the established views, we have solved the structure of the complex of the CPT G215S/A251G/T257A/D260G/T262D mutant with the transition state analogue N-sulfamoyl-L-phenylalanine at a resolution of 1.35 Å and compared it with the structure of similar complex formed by CPB. The comparative study revealed a previously underestimated structural determinant of the substrate specificity of metallocarboxypeptidases and showed that even if substitution of five amino acid residues in the primary specificity pocket results in its almost complete structural correspondence to the analogous pocket in CPB, this does not lead to fundamental changes in the substrate specificity of the mutant enzyme due to the differences in the structure of the mobile loop located at the active site entrance that affects the substrate-induced conformational rearrangements of the active site.

Design and fabrication of novel thiourea coordination compounds as potent inhibitors of bacterial growth

A new thiourea ligand (HL), namely N-(4-chlorophenyl)morpholine-4-carbothioamide and its Co(III), Ni(II) and Ag(I) complexes (1a, 1b and 1c) were synthesized and investigated by Fourier-transform infrared, ¹H NMR and UV-visible spectroscopies. The compounds HL and 1c were characterized by single-crystal X-ray crystallography revealing the triclinic space group P[Formula: see text] for both compounds. The inhibitory effect of HL ligand, 1a, 1b, and 1c complexes was investigated with in vitro tests on Gram-positive and Gram-negative bacteria. For the 1c complex, the results showed that the coordination of the HL to Ag(I) ion increased its antibacterial effect especially against E. coli. The assays also indicated that for the same bacteria strains, the new complexes showed higher activity than the ligand, with the relative activity 1c > 1b > 1a > HL. Moreover, all samples were more suitable antimicrobial agents against the Gram-negative than those of the Gram-positive bacteria. Eventually, the relationship between the structure and bactericidal activities of these specimens was examined by calculating frontier molecular orbital (HOMO and LUMO) energies using density functional theory method at the 6-31 G*/LANL2DZ level of theory.

Spin Crossover in a Hexaamineiron(II) Complex: Experimental Confirmation of a Computational Prediction

Single crystal structural analysis of [FeII (tame)2 ]Cl2 ⋅MeOH (tame=1,1,1-tris(aminomethyl)ethane) as a function of temperature reveals a smooth crossover between a high temperature high-spin octahedral d6 state and a low temperature low-spin ground state without change of the symmetry of the crystal structure. The temperature at which the high and low spin states are present in equal proportions is T1/2 =140 K. Single crystal, variable-temperature optical spectroscopy of [FeII (tame)2 ]Cl2 ⋅MeOH is consistent with this change in electronic ground state. These experimental results confirm the spin activity predicted for [FeII (tame)2 ]2+ during its de novo artificial evolution design as a spin-crossover complex [Chem. Inf.

MODEL

2015, 55, 1844], offering the first experimental validation of a functional transition-metal complex predicted by such in silico molecular design methods. Additional quantum chemical calculations offer, together with the crystal structure analysis, insight into the role of spin-passive structural components. A thermodynamic analysis based on an Ising-like mean field model (Slichter-Drickammer approximation) provides estimates of the enthalpy, entropy and cooperativity of the crossover between the high and low spin states.

Design, physico-chemical and pre-clinical evaluation of a homo-bivalent 99mTc-(BTZ)2DTPA radioligand for targeting dimeric 5-HT1A/5-HT7 receptors

A ^99mTc-labelled bis-benzothiazolone-DTPA radio-complex as a SPECT neuroimaging agent.