Shohami E, Koren R
Biochem J. 1979 Feb 15;178(2):271-7. doi: 10.1042/bj1780271.
A fluorescent derivative of 6-mercaptoguanosine, S-(N-dansylaminoethyl)-6-mercaptoguanosine, was synthesized, and found to be a strong inhibitor of the uridine transport system of erythrocyte (Ki approximately 0.3 microM). The emission spectrum of this compound has peaks at 400 and 550 nm. The emission at 550, but not that a 400 nm, in environment-sensitive. A method was devised for preparing a suspension of erythrocyte-membrane fragments with sufficiently low light scattering so that a detailed study could be made of the fluorescence of the probe when bound to membranes. Direct binding measurements showed the existence of a tight binding site, with a dissociation constant of the same order of magnitude as the inhibition constant. Binding of probe and substrate are not mutually exclusive, but the fluorescence and affinity of the bound probe are sensitive to the presence of uridine. The emission spectrum suggests that the bound probe penetrates into the bilayer region of the membrane.
合成了6-巯基鸟苷的荧光衍生物S-(N-丹磺酰氨基乙基)-6-巯基鸟苷，发现它是红细胞尿苷转运系统的强抑制剂（Ki约为0.3微摩尔）。该化合物的发射光谱在400和550纳米处有峰值。550纳米处的发射是环境敏感的，而400纳米处的发射则不是。设计了一种制备具有足够低光散射的红细胞膜片段悬浮液的方法，以便能够详细研究探针与膜结合时的荧光。直接结合测量表明存在一个紧密结合位点，其解离常数与抑制常数处于同一数量级。探针和底物的结合并非相互排斥，但结合探针的荧光和亲和力对尿苷的存在敏感。发射光谱表明结合的探针渗透到膜的双层区域。
