Theory of the Electrostatic Surface Potential and Intrinsic Dipole Moments at the Mixed Ionic Electronic Conductor (MIEC)-gas Interface

The local activation overpotential describes the electrostatic potential shift away from equilibrium at an electrode/electrolyte interface. This electrostatic potential is not entirely satisfactory for describing the reaction kinetics of a...

Crystal structure of chloroplastic thioredoxin z defines a novel type-specific target recognition

Thioredoxins (TRXs) are ubiquitous disulfide oxidoreductases structured according to a highly conserved fold. TRXs are involved in a myriad of different processes through a common chemical mechanism. Plant thioredoxins evolved into seven types with diverse subcellular localization and distinct protein targets selectivity. Five TRX types coexist in the chloroplast, with yet scarcely described specificities. We solved the first crystal structure of a chloroplastic z-type TRX, revealing a conserved TRX fold with an original electrostatic surface potential surrounding the redox site. This recognition surface is distinct from all other known TRX types from plant and non-plant sources and is exclusively conserved in plant z-type TRXs. We show that this electronegative surface endows TRXz with a capacity to activate the photosynthetic Calvin-Benson cycle enzyme phosphoribulokinase. TRXz distinct electronegative surface thereby extends the repertoire of TRX-target recognitions.

Chemical Tools for Study of Phosphohistidine: Generation of Selective τ-Phosphohistidine and π-Phosphohistidine Antibodies

Non-hydrolysable stable analogues of τ-pHis and π-pHis have been designed using electrostatic surface potential calculations, and subsequently synthesized. The τ-pHis and π-pHis analogues (phosphopyrazole <b>8 </b>and pyridyl amino amide <b>13</b>, respectively)<b> </b>were used as haptens to generate pHis polyclonal antibodies. <a>Both τ-pHis and π-pHis conjugates in the form of a BSA-glutaraldehyde-τ-pHis and BSA-glutaraldehyde-π-pHis</a> were synthesized and characterized by ³¹P NMR spectroscopy. Commercially available τ-pHis (SC56-2) and π-pHis (SC1-1; SC50-3) monoclonal antibodies were used to show that the BSA-G-τ-pHis and BSA-G-π-pHis conjugates could be used to assess the selectivity of pHis antibodies in a competitive ELISA. Subsequently, the selectivity of the generated pHis antibodies generated using phosphopyrazole <b>8 </b>and pyridyl amino amide <b>13</b> as haptens was assessed by competitive ELISA against His, pSer, pThr, pTyr, τ-pHis and π-pHis. Antibodies generated using the phosphopyrazole <b>8</b> as a hapten were found to be selective for τ-pHis, and antibodies generated using the <a>pyridyl amino amide <b>13</b> </a>were found to be selective for π-pHis. Both τ- and π-pHis antibodies were shown to be effective in immunological experiments, including ELISA, western blot, and immunofluorescence. The τ-pHis antibody was also shown to be useful in the immunoprecipitation of proteins containing pHis

Chemical Tools for Study of Phosphohistidine: Generation of Selective τ-Phosphohistidine and π-Phosphohistidine Antibodies

Non-hydrolysable stable analogues of τ-pHis and π-pHis have been designed using electrostatic surface potential calculations, and subsequently synthesized. The τ-pHis and π-pHis analogues (phosphopyrazole <b>8 </b>and pyridyl amino amide <b>13</b>, respectively)<b> </b>were used as haptens to generate pHis polyclonal antibodies. <a>Both τ-pHis and π-pHis conjugates in the form of a BSA-glutaraldehyde-τ-pHis and BSA-glutaraldehyde-π-pHis</a> were synthesized and characterized by ³¹P NMR spectroscopy. Commercially available τ-pHis (SC56-2) and π-pHis (SC1-1; SC50-3) monoclonal antibodies were used to show that the BSA-G-τ-pHis and BSA-G-π-pHis conjugates could be used to assess the selectivity of pHis antibodies in a competitive ELISA. Subsequently, the selectivity of the generated pHis antibodies generated using phosphopyrazole <b>8 </b>and pyridyl amino amide <b>13</b> as haptens was assessed by competitive ELISA against His, pSer, pThr, pTyr, τ-pHis and π-pHis. Antibodies generated using the phosphopyrazole <b>8</b> as a hapten were found to be selective for τ-pHis, and antibodies generated using the <a>pyridyl amino amide <b>13</b> </a>were found to be selective for π-pHis. Both τ- and π-pHis antibodies were shown to be effective in immunological experiments, including ELISA, western blot, and immunofluorescence. The τ-pHis antibody was also shown to be useful in the immunoprecipitation of proteins containing pHis

No regioselectivity for the steroid α-face in cocrystallization of exemestane with aromatic cocrystal formers based on phenanthrene and pyrene

The anti-cancer steroidal drug exemestane presents significantly different behavior in cocrystallization with arenes compared with the previously explored steroid progesterone. Mechanochemical and solution-based cocrystallization of exemestane with hydroxy derivatives of phenanthrene and pyrene leads to the formation of cocrystals exhibiting clear O–H···O type arene-steroid hydrogen bonds. So far, exemestane and 1-hydroxypyrene have been observed to form only one type of cocrystal, with the 1:1 stoichiometric ratio of the two components. However, there are two stoichiometric variations of the cocrystal of 9-hydroxyphenanthrene and exemestane, with the arene:steroid stoichiometric ratio of either 1:1 or 1:2. Importantly, although cocrystallization of progesterone with the same arene cocrystal formers was previously reported to take place regioselectively through α···π contacts between the α-face of the steroid and the π-electron surface of the arene, the herein explored cocrystals of exemestane reveal α···π and β···π contacts, as well as sidewise interactions involving the arene π-system and different edges of the steroid molecule. The loss of regioselectivity for the steroid α-face in cocrystallization with the two monohydroxylated arenes is tentatively explained by the highly positive electrostatic surface potential of the steroid β-face and a diminished number of C–H groups on the α-face of exemestane compared with progesterone.