Niamaa D, Bat-Erdéné O, Burshteĭn E A
Mol Biol (Mosk). 1984 Jul-Aug;18(4):972-8.
In order to investigate effects of temperature in the physiological range (from 10 to 50 degrees C) on structural, physical and functional properties of the N-form of human serum albumin (HSA), the temperature dependences of fluorescence parameters of Trp-214 residue of HSA and of the specifically bound dye ANS, as well as of association constants of ANS binding in the primary and secondary binding sites on HSA molecule were measured. The temperature-induced changes of these properties of HSA are essentially dependent on pH (7.0 or 5,6) and ionic strength (0.001-0.008 or 0.2 M NaCl). At pH 7.0 and 0.2 M NaCl the environment of Trp-214 remained invariant at temperature changes between 10 and 50 degrees C. On the other hand, the affinity to ANS of a primary binding site doubled and that of secondary ones halved. These affinity changes seem to be due, are least partly, to the heating-induced dissociation of Cl-ions, which are inhibitors of the primary dye binding. By lowering pH (to 5.6) and ionic strength the temperature-induced changes in the Trp-214 environment were observed. The changes are interpreted as indole group transition into the buried region, inaccesible to water (the "closing" of a structural slit). The affinity of secondary binding sites of ANS was halved.
为了研究生理范围内（10至50摄氏度）的温度对人血清白蛋白（HSA）N形式的结构、物理和功能特性的影响，测量了HSA的Trp-214残基和特异性结合染料ANS的荧光参数的温度依赖性，以及HSA分子上一级和二级结合位点的ANS结合常数。HSA这些特性的温度诱导变化基本上取决于pH值（7.0或5.6）和离子强度（0.001 - 0.008或0.2 M NaCl）。在pH 7.0和0.2 M NaCl条件下，当温度在10至50摄氏度之间变化时，Trp-214的环境保持不变。另一方面，一级结合位点对ANS的亲和力增加了一倍，而二级结合位点的亲和力减半。这些亲和力变化似乎至少部分是由于加热导致Cl-离子解离，Cl-离子是染料一级结合的抑制剂。通过降低pH值（至5.6）和离子强度，观察到Trp-214环境的温度诱导变化。这些变化被解释为吲哚基团转变为水不可及的埋藏区域（结构裂隙的“闭合”）。ANS二级结合位点的亲和力减半。
