The successive protonation steps occurring in 2,2′;6′,2″-terpyridine (L1) are characterized by a strong affinity for the first entering proton (ΔG(connect)(H,L1) = −17 kJ/mol) followed by allosteric anticooperativity (ΔE(interaction)(H,H,L1) = 6 kJ/mol), a behavior mirrored by 2,6-bis(azaindolyl)pyridine (L2) despite the extension of the chelate ring size from five members (L1) to six members (...

Relying upon the basic tenets of scientific modeling, an ansatz for the evaluation of proton affinity of molecules are evolved in terms of a four component model. The components of the model chosen are global descriptors like ionization energies, global softness, electronegativity and electrophilicity index. These akin quantum mechanical descriptors of atoms and molecules are linked with the ch...

The brush-border membrane of renal epithelial cells contains PEPT1 and PEPT2 proteins that are rheogenic carriers for short-chain peptides. The carrier proteins display a distinct surface expression pattern along the proximal tubule, suggesting that initially di- and tripeptides, either filtered or released by surface-bound hydrolases from larger oligopeptides, are taken up by the low-affinity ...

The present study involved the preparation of organomercury and organotellurium compounds derived from camphor (2-amino-5-methylphenyl) mercury (II) chloride their derivatives by a condensation reaction. Characterization studied was carried out using infrared spectrum (IR), proton nuclear magnetic resonance (1H NMR), elemental analysis (C.H.N). molecular structure investigated density functiona...

Glutamate transport by the neuronal excitatory amino acid carrier (EAAC1) is accompanied by the coupled movement of one proton across the membrane. We have demonstrated previously that the cotransported proton binds to the carrier in the absence of glutamate and, thus, modulates the EAAC1 affinity for glutamate. Here, we used site-directed mutagenesis together with a rapid kinetic technique tha...

ExbB and ExbD proteins are part of the TonB-dependent energy transduction system and are encoded by the exb operon in Escherichia coli. TonB, the energy transducer, appears to go through a cycle during energy transduction, with the absence of both ExbB and ExbD creating blocks at two points: (i) in the inability of TonB to respond to the cytoplasmic membrane proton motive force and (ii) in the ...

Monolignol binding to the peroxidase active site is the first step in lignin polymerization in plant cell walls. Using molecular dynamics, docking, and free energy perturbation calculations, we investigate the binding of monolignols to horseradish peroxidase C. Our results suggest that p-coumaryl alcohol has the strongest binding affinity followed by sinapyl and coniferyl alcohol. Stacking inte...

The ClC protein family includes voltage-gated chloride channels and chloride/proton exchangers. In eukaryotes, ClC proteins regulate membrane potential of excitable cells, contribute to epithelial transport, and aid in lysosomal acidification. Although structure/function studies of ClC proteins have been aided greatly by the available crystal structures of a bacterial ClC chloride/proton exchan...

Heme-copper oxidases terminate the respiratory chain in many eukaryotes and prokaryotes as the final electron acceptors. They catalyze the reduction of molecular oxygen to water, and conserve the free-energy by proton pumping across the inner mitochondrial membrane or plasma membrane of bacteria. This leads to the generation of an electrochemical gradient across the membrane, which is utilized ...

In this paper, we report the measurement of the degree of analyte fragmentation in AP-MALDI as a function of the matrix and of the laser fluence. The analytes include p-OCH3-benzylpyridinium, three peptides containing the sequence EEPP (which cleave very efficiently at the E-P site), and three deoxynucleosides (dA, dG, and dC), which lose the neutral sugar to give the protonated base. We found ...