A calorimetric study of Ca2+ binding by the parvalbumin of the toad (Bufo): distinguishable binding sites in the molecule

FEBS Letters

Yamada, Kazuhiro¹  Tanokura, Masaru¹  Imaizumi, Masamoto¹ 

[1] Department of Physiology, Medical College of Oita, Hasama, Oita 879-56, Japan

关键词: Microcalorimetry Parvalbumin Ca2+ binding Mg2+ binding Enthalpy titration (Toad);   

DOI  :  10.1016/0014-5793(86)81087-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Microcalorimetric titrations of the major isotype of parvalbumin (tPA) from toad (Bufo) skeletal muscle, with Ca²⁺ in the presence and absence of Mg²⁺ and with Mg²⁺ in the absence of Ca²⁺, have been carried out at 25°C and pH 7.O. The results indicate that the two binding sites in each molecule are distinguishable from each other for both Ca²⁺ binding and Mg²⁺ binding. Such a characteristic is distinctly different from those of other parvalbumins. The enthalpy changes determined are distinctly different from those of bullfrog parvalbumins on Ca²⁺ or Mg²⁺ binding, but are similar to those on Mg²⁺-Ca²⁺ exchange. The results indicate that the reaction of Mg²⁺-Ca²⁺ exchange is driven almost entirely by the large favorable enthalpy change.

【 授权许可】

Unknown