著者

中垣 正幸 嶋林 三郎 早川 栄治 小槻 節

出版者

公益社団法人 日本薬学会

雑誌

YAKUGAKU ZASSHI (ISSN:00316903)

巻号頁・発行日

vol.99, no.6, pp.618-627, 1979-06-25 (Released:2008-05-30)

参考文献数

11

被引用文献数

5 3

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The amounts of both Ca2+ and Na+, x and y, respectively, bound to C-type chondroitin sulfate (Chs) from an aqueous solution of CaCl2 mixed with NaCl were obtained by the membrane equilibrium method. To estimate x and y under the effect of the Donnan equilibrium, [Ca2+] and [Cl-] for both sides of the dialysing tube and [Chs] for the inner side were analysed. The binding isotherm for Ca2+ was of the Langmuir type, and both x and kCa2+, the binding constant for Ca2+, decreased with ionic strength, J. On the other hand, the binding isotherm for Na+ was not of the Langmuir type but its shape was explained as the competitive adsorption of the two components, Na+ and Ca2+, because Ca2+ binds more strongly to Chs than Na+ and, therefore, the effect of coexistence of Ca2+ with Na+ cannot be neglected when the Na+ binding is examined. It was also suggested that y and kNa+ decreases with J when the amount of the occupied site by the Ca2+ is kept constant at x. The degree of the ionization, z, of Chs was found to be 0.40-0.41 for Na2Chs and 0.20-0.21 for CaChs by this membrane equilibrium method assuming x+y+z=1. These values coincide with those obtained from the vapour pressure osmometry by the authors and with the literature values calculated with considering the Manning theory.