Damaschun G, Damaschun H, Gast K, Misselwitz R, Müller J J, Pfeil W, Zirwer D
Max Delbrück Center for Molecular Medicine, Berlin-Buch, Germany.
Biochemistry. 1993 Aug 3;32(30):7739-46. doi: 10.1021/bi00081a019.
The temperature-dependent conformational equilibrium of 3-phosphoglycerate kinase has been studied in the temperature range from 1 to 30 degrees C by means of dynamic light scattering, small-angle X-ray scattering, differential scanning calorimetry, circular dichroism spectroscopy, and fluorescence spectroscopy. At 28 degrees C and in the presence of 0.7 M guanidine hydrochloride (GuHCl), the radius of gyration (RG) and the Stokes radius (RS) are 2.44 and 3.09 nm, respectively. Decreasing the temperature effects unfolding of the molecule, a process that involves two stages. The two stages correspond to the successive unfolding of the N-terminal and C-terminal domains. The peak maxima of the excess heat capacity, determined from differential calorimetric scans, extrapolated to 0 scan rate, are positioned at 16.5 degrees C for the N-terminal domain and at 6.3 degrees C for the C-terminal domain. At 4.5 degrees C, the radius of gyration and the Stokes radius increase to 7.8 and 4.8 nm, respectively. The persistence length and the length of the statistical chain segment of the unfolded polypeptide chain are 1.74 and 3.48 nm, corresponding to five and ten amino acids, respectively. At 1 degrees C, the dimensions of the unfolded chain nearly agree with the predicted dimensions under theta conditions. Thus, the conformational changes upon cold denaturation can be described by a transition from a compactly folded molecule to a random coil. The conformation-dependent ratio rho = RGRS-1 increases from rho = 0.79 to rho = 1.63. The volume of the unfolded chain is 30 times larger than that of the folded chain in the native state.(ABSTRACT TRUNCATED AT 250 WORDS)
通过动态光散射、小角X射线散射、差示扫描量热法、圆二色光谱法和荧光光谱法，研究了3-磷酸甘油酸激酶在1至30摄氏度温度范围内与温度相关的构象平衡。在28摄氏度且存在0.7 M盐酸胍（GuHCl）的条件下，回转半径（RG）和斯托克斯半径（RS）分别为2.44和3.09 nm。降低温度会导致分子展开，该过程涉及两个阶段。这两个阶段分别对应N端和C端结构域的相继展开。由差示量热扫描确定并外推至0扫描速率的过量热容的峰值最大值，N端结构域位于16.5摄氏度，C端结构域位于6.3摄氏度。在4.5摄氏度时，回转半径和斯托克斯半径分别增加到7.8和4.8 nm。展开的多肽链的持久长度和统计链段长度分别为1.74和3.48 nm，分别对应五个和十个氨基酸。在1摄氏度时，展开链的尺寸与θ条件下预测的尺寸几乎一致。因此，冷变性时的构象变化可以描述为从紧密折叠的分子转变为无规卷曲。构象相关比率rho = RGRS-1从rho = 0.79增加到rho = 。展开链的体积比天然状态下折叠链的体积大30倍。（摘要截短于250字） （注：原文中“rho = 1.63”后少了内容，已按原文翻译）
