Sogami M, Itoh K B, Nemoto Y
Biochim Biophys Acta. 1975 Jun 26;393(2):446-59. doi: 10.1016/0005-2795(75)90073-2.
The acid-induced isomerization (the N-F transition) and expansion of bovine plasma albumin were studied by measuring fluorescence polarization and lifetime of the excited state of tryptophyl fluorophors. Most of the changes (decreases) in the reciprocal of fluorescence polarization and lifetime of the excited state correlated exactly with the N-F1 transition and/or the initial part of the N-F transition. These findings suggest that though the N-F transition is the cooperative pH-dependent conformational transition, the N-F transition clearly involves an intermediate step, such as the N-F1 and F1-F2 transitions. Rotational relaxation times for the N- and F-forms obtained by Perrin plot of tryptophyl fluorescence polarization were approximately 75 and 120-180 ns, respectively. The unexpected short rotational relaxation time of 75 ns of the N-form might be due to the rotational freedom of the tryptophyl side chain itself and/or of small flexible loci where tryptophyl fluorophors attach.
通过测量色氨酸荧光团激发态的荧光偏振和寿命，研究了酸诱导的牛血清白蛋白异构化（N-F转变）和膨胀。激发态荧光偏振倒数和寿命的大多数变化（降低）与N-F1转变和/或N-F转变的初始部分精确相关。这些发现表明，尽管N-F转变是协同的pH依赖性构象转变，但N-F转变显然涉及一个中间步骤，如N-F1和F1-F2转变。通过色氨酸荧光偏振的佩林图获得的N型和F型的旋转弛豫时间分别约为75和120-180纳秒。N型意外的75纳秒短旋转弛豫时间可能是由于色氨酸侧链本身的旋转自由度和/或色氨酸荧光团附着的小柔性位点的旋转自由度。
