A novel technique to estimate the distribution state of carboxyl groups within submicron-sized, carboxylated polymer particles was proposed. For the purpose, carboxyl groups in two kinds of butyl methacrylate-methacrylic acid copolymer emulsion, which were prepared by emulsion copolymerizations with different monomer addition methods, were titrated by isothermal titration calorimetry with an ex...

To explore electrostatic interactions in ubiquitin, pK(a) values have been determined by NMR for all 12 carboxyl groups in wild-type ubiquitin and in variants where single lysines have been replaced by neutral residues. Aspartate pK(a) values in ubiquitin range from 3.1 to 3.8 and are generally less than model compound values. Most aspartate pK(a) values are within 0.2 pH unit of those predicte...

Native insulin causes fusion of negatively charged liposomes in the pH range from 3.0 to 5.5. In marked contrast, insulin with all three amino groups succinylated did not show fusion ability at any pH. On the other hand, insulin amidated with glycine methyl ester with all six carboxyl groups blocked shifted its activity to higher pH, showing a pH range of activity from 3.0 to 7.4. When the carb...

Chemical modification and electron spin resonance techniques were used to study the topography of carboxyl residues in purple membranes. The results showed that buried carboxyl groups are )ocated in hydrophobic protein domains at least 16 A from the membrane surface, and that the carboxyl-terminal tail is partially immobilized. Carboxyl groups on bacteriorhodopsin in purple membranes...

The synthesis of coordination polymers (e.g. Prussian blue) is as old modern chemistry itself, but never stops surprising people. We here report superconductivity observed a designer polymer system sporting the chemically soft mercaptan and hard carboxyl groups. mercapto-carboxyl (dubbed Mercarb, or QiuSuo in Mandarin Pinyin) synergy hints at Daoism carries over from molecular to solid state: s...

In the title compound, C(6)H(16)N(+)·C(7)H(5)O(4) (-), the hy-droxy groups of the 3,4-dihy-droxy-benzoate anion form O-H⋯O hydrogen bonds to the carboxyl-ate groups of two adjacent anions, generating layers propagating in the ac plane. The triethyl-ammonium cations lie between these layers, forming N-H⋯O hydrogen bonds to the carboxyl-ate groups of the anions. The structure is consolidated by w...

In the title compound, {[Zn(2)(C(16)H(4)I(2)O(8))(H(2)O)(4)]·2H(2)O}(n), two crystallographically independent Zn(II) atoms are each located on a twofold rotation axis. Both Zn(II) atoms are in distorted octa-hedral coordination geometries: one is coordinated by six O atoms from four carboxyl-ate groups, while the other is coordinated by two carboxyl-ate groups and four water mol-ecules. The tet...

In the title coordination polymer, [Pb(C(7)H(3)NO(4))](n), the Pb(II) ion is eight-coordinated in a distorted square-anti-prismatic geometry formed by one pyridine N atom and seven carboxyl-ate O atoms from four pyridine-2,3-dicarboxyl-ate (pda) anions. In the pda anion, the dihedral angles between the pyridine ring and carboxyl-ate groups are 19.5 (6) and 73.3 (6)°. The carboxyl-ate groups of ...

Six dissociable groups exist in tetrahydrofolic acid in the range Ho -3.0 to pH 14. The assignments in tetrahydrofolic acid by titrimetric and spectrophotometric comparisons with model compounds, +uninobenzoylglutamic acid and 2-amino-6,7-dimethyl-5,6,7,8-tetrahydro-4-pteridinone, are as follows: acidic ionization of amide, pK’ 10.5; Ns, pK’ 4.82; y-carboxyl, pK’ 4.8; cr-carboxyl, pK’ 3.5; N1, ...

A universal route to GQDs is developed based on "solution phase-based scissor" methods. The PL centers of the GQDs are systematically studied and are proved to be the surface state. This is related to the hybridization structure of the edge groups and the connected partial graphene core. Through experiment and analysis, we have preliminarily proved that the efficient edge groups for green emiss...