Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DISSOCIATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed2004

Foldon, the natural trimerization domain of T4 fibritin, dissociates into a monomeric A-state form containing a stable beta-hairpin: atomic details of trimer dissociation and local beta-hairpin stability from residual dipolar couplings.

The C-terminal domain of T4 fibritin (foldon) is obligatory for the formation of the fibritin trimer structure and can be used as an artificial trimerization domain. Its native structure consists of a trimeric beta-hairpin propeller. At low pH, the foldon trimer disintegrates into a monomeric (A-state) form that has similar properties as that of an early intermediate of the trimer folding pathway. The formation of this A-state monomer from the trimer, its structure, thermodynamic stability, equilibrium association and folding dynamics have been characterized to atomic detail by modern high-resolution NMR techniques. The foldon A-state monomer forms a beta-hairpin with intact and stable H-bonds that is similar to the monomer in the foldon trimer, but lacks a defined structure in its N and C-terminal parts. Its thermodynamic stability in pure water is comparable to designed hairpins stabilized in alcohol/water mixtures. Details of the thermal unfolding of the foldon A-state have been characterized by chemical shifts and residual dipolar couplings (RDCs) detected in inert, mechanically stretched polyacrylamide gels. At the onset of the thermal transition, uniform relative changes in RDC values indicate a uniform decrease of local N-HN and Calpha-Halpha order parameters for the hairpin strand residues. In contrast, near-turn residues show particular thermal stability in RDC values and hence in local order parameters. This coincides with increased transition temperatures of the beta-turn residues observed by chemical shifts. At high temperatures, the RDCs converge to non-zero average values consistent with predictions from random chain polymer models. Residue-specific deviations above the unfolding transition reveal the persistence of residual order around proline residues, large hydrophobic residues and at the beta-turn.

Hydrogen Bonding↗
PubMed1985

Quin 2: the dissociation constants of its Ca2+ and Mg2+ complexes and its use in a fluorimetric method for determining the dissociation of Ca2+-protein complexes.

Fluorimetric or spectrophotometric titrations with the appropriate cations gave Kd values of 2.9 +/- 0.2 nM and 89 +/- 5 microM respectively for the Ca2+ and Mg2+ complexes of quin 2 at pH 7.5. Mixtures of quin 2 and vitamin D-dependent Ca2+-binding protein from pig duodenum were titrated fluorimetrically with Ca2+ in the absence or presence of Mg2+. These measurements were used with the Kd values of the Ca2+ and Mg2+ complexes of quin 2 to obtain Kd or apparent Kd values for Ca2+-protein complexes ranging from 5 nM to 5 microM with good accuracy.

Aminoquinolines↗