Cystine as Ligand of Calcium(II) and Magnesium(II) in Two Ionic Media and at Two Different Temperatures (25 and 37 °C)

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• 作者：Emilio Bottari ; Maria Rosa Festa ; Lorella Gentile
• 关键词：Calcium(II)–cystine complexes ; Magnesium(II)–cystine complexes ; Stability constants in physiological conditions ; Cystine solubility ; Potentiometric measurements
• 刊名：Journal of Solution Chemistry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：46
• 期：1
• 页码：215-224
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry; Industrial Chemistry/Chemical Engineering; Geochemistry; Oceanography; Inorganic Chemistry; Condensed Matter Physics;
• 出版者：Springer US
• ISSN：1572-8927
• 卷排序：46

文摘

Cystine plays an important role in human physiology, it is the precursor of cysteine. Cystine is the molecular form preferred by the immunity cellules system, included macrophages. Although slightly soluble, it can be a ligand towards cations because it is a sulfur-containing amino acid. Because of the physiological importance of calcium(II) and magnesium(II), complex formation between these cations and cystine was studied potentiometrically by employing electrochemical cells involving glass electrodes. The investigation was performed at two temperatures (25 and 37) °C and in two ionic media (1.00 and 0.15 mol·dm−3 NaCl). In both ionic media, the adoption of a constant ionic medium allows extension of the investigation to a large range of reagent concentration. As the formation of weak complexes was foreseen, the low solubility of cystine is an advantage. Experimental data can be explained in any case by assuming the formation of mononuclear complexes in the presence of both calcium(II) and magnesium(II). The relative stability constants were determined.