Ultracentrifugal Analysis of Protein-bound and Free Calcium in Human Serum

Carrier-Based Ion-Selective Electrodes and Bulk Optodes. 2. Ionophores for Potentiometric and Optical Sensors

“…286,586 Moreover, a temperature dependence of the free calcium concentration was reported. 587 Contrary to theoretical expectations, acetate interference was reported to increase with the concentration of lipophilic anionic sites in ETH 1001 (Ca 2+ -5) membranes. 588 In addition to reasons discussed above for a similar case of K + solid-contact electrodes by the same authors, 391 doubts on this interpretation arise from the fact that high acetate concentrations strongly affect the responses of nearly all the Ca 2+ sensors tested in that particular investigation.…”

“…A review of the history of Ca 2+ measurements with ISEs from the clinical point of view has discussed the properties of many commercial clinical analyzers and well documented how organophosphate carriers started to be replaced by neutral amide carriers in the end of the 1970s. , General comments on the use of ISEs in clinical chemistry were given above (cf. section II.3) and apply also to Ca 2+ measurements. ,,,,,− Furthermore, binding of Ca 2+ to heparin may cause erroneous Ca 2+ determinations. , Special care must also be taken to prevent loss of CO 2 from the sample because the amount of Ca 2+ bound to proteins is very large, , and the concentration of free Ca 2+ depends even more strongly on the pH than in the case of Mg 2+ . , Moreover, a temperature dependence of the free calcium concentration was reported . Contrary to theoretical expectations, acetate interference was reported to increase with the concentration of lipophilic anionic sites in ETH 1001 ( Ca 2+ -5 ) membranes .…”

Fractionation of calcium and magnesium in equine serum

“…19 However, our percentage of pCa is in good agreement with most human values obtained by ultrafiltration and ultracentrifugation. [20][21][22][23] It is noteworthy that Holley and Evans 19 also analyzed some samples of human serum to validate the ultrafiltration procedure and the values that they reported for pCa were also slightly lower than those found in other human studies. [20][21][22][23] The slightly higher percentage of pCa found in our study may be the result of a greater ability of the ultrafiltration membrane to retain proteins.…”

Quantitative Microdialysis: Experimental Protocol and Software for Small Molecule Protein Affinity Determination and for Exclusion of Compounds with Poor Physicochemical Properties

“…Then, since the total amount of protein is known, the binding affinity of the complex can be calculated. Many highly sophisticated techniques have been developed during the last decades to analyse and quantify the interactions of small molecules with proteins, including multiple modes of fluorescence spectroscopy [5], nuclear magnetic resonance (NMR) [6], mass spectrometry [7], affinity selection [8,9] and size exclusion chromatography [10], just to name a few. We apply all of the above in our hit and lead identification projects.…”