Anti-Human HBZ (a.a. 1-142) Polyclonal antibody

Electronic structure calculations were carried out to prove the stability of the 1,4-benzoquinone-benzoic acid adduct, Q(HBz), linked by hydrogen bonds. The Q(HBz) geometry was optimized using the density functional theory (DFT), with gradient-corrected and hybrid exchange-correlation functionals, and MphillerPlesset perturbation theory (MP2) with DZP plus diffuse functions and TZVP basis sets; the fitting approach on the electron density was tested for DFT calculations with the TZVP/A2 basis set. Two stable planar conformers Q(HBz) were determined and confirmed by a frequency analysis. Conformer I has two hydrogen bonds, one O-H ... O-Q and one weak C-Q-H...O, where O-Q is a quinone oxygen and C-Q corresponds to a quinone (x-carbon. In the conformer 2 the Q(HBz) adduct is stabilized also with two hydrogen bonds, one is C-Q-H ... O like the conformer 1, and the other one is a C-B-H ... O bond, where C-B is a carbon that belongs to the ring of the benzoic acid. Binding energies for both conformers are reported, a good agreement between DFT and MP2 results was obtained only when the basis set superposition error is included. Furthermore this agreement is better between DFT with a hybrid exchange-correlation functional and the MP2 method. The binding energy at our best level of theory was -7.7 kcal/mol for conformer 1 and -3.7 kcal/mol for conformer 2. Additionally to the theoretical study, a novel electrochemical method is proposed to characterize the Q(HBz) adduct. The electrochemical characterization of the neutral-neutral association by hydrogen bonds was performed in DMSO, on the basis of voltammetric current measurements. The method stems from the fact that the diffusion coefficient of the electroactive compound is modified by effect of the association, of Q with HBz, which provokes significant variations in the voltammetric current peak. By using this variation, it was determined that the Q and HBz are associated with a 1: 1 stoichiometry with a conditional association constant of 12 M-1. This electrochemical approach represents an alternative tool to evaluate association constants involving neutral species, in conditions where the spectroscopic techniques are difficult to apply.

HTLV-I bZIP factor (HBZ) contains a C-terminal zipper domain involved in its interaction with c-Jun. This interaction leads to a reduction of c-Jun DNA-binding activity and prevents the protein from activating transcription of AP-1-dependent promoters. However, it remained unclear whether the negative effect of HBZ-SP1 was due to its weak DNA-binding activity or to its capacity to target Cellular factors to transcriptionally-inactive nuclear bodies. To answer this question, we produced a Mutant in which specific residues present in the modulatory and DNA-binding domain of HBZ-SP1 were substituted for the corresponding c-Fos amino acids to improve the DNA-binding activity of the c-Jun/HBZ-SP1 heterodimer. The stability of the mutant, its interaction with c-Jun, DNA-binding activity of the resulting heterodimer, and its effect on the c-Jun activity were tested. In conclusion, we demonstrate that the repression of c-Jun activity in vivo is mainly due to the HBZ-SP1-mediated sequestration of c-Jun to the HBZ-NBs. (C) 2009 Elsevier Inc. All rights reserved.