Analysis of a calcium ion binding system composed of two different sites.

摘要: Using murexide (Mx), a metallochromic indicator, and dual wavelength spectrophotometer with high signal-to-noise ratio, the Ca(++) binding in system containing two classes of sites was studied. Solutions solute one or without such were titrated using Mx as an indicator free concentration. Since curvilinear Scatchard plots are obtained from titration curves solutes sites, computer program developed to resolve into linear partial plots, each corresponding single class site. The validity procedure examined solutions ethylene glycol bis(beta-aminoethyl)-N-N'-tetraacetic acid, adenosine triphosphate (EGTA, ATP), mixture thereof. method also applied biological material it found that protein fraction isolated rat skeletal muscle sarcotubular membranes, termed Fraction-2 (Fr-2), has for Ca(++); association constants affinity site low 4.3 x 10(5) M(-1) 9 10(3) M(-1), respectively. advantages limitations this methodology discussed.