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.
D000634:Aminoquinolines / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D046911:Macromolecular Substances; D008274:Magnesium / Q000378:metabolism*; D008722:Methods; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D000634:Aminoquinolines; D002135:Calcium-Binding Proteins; D005456:Fluorescent Dyes; D046911:Macromolecular Substances; D064030:S100 Calcium Binding Protein G; D008274:Magnesium; C035739:Quin2; D002118:Calcium