ANS fluorescence: Potential to augment the identification of the external binding sites of proteins
ANS fluorescence: Potential to augment the identification of the external binding sites of proteins
复制标题
DOI：
10.1016/j.bbapap.2007.01.002
复制
发表时间：
2007-03-01
影响因子：
3.2
通讯作者：
Glasgow, Ben J.
中科院分区：
文献类型：
--
作者：
Gasymov, Oktay K.;Glasgow, Ben J.
8 - 苯胺基 - 1 - 萘磺酸（ANS）被认为可通过离子对形成与蛋白质和多氨基酸的阳离子基团紧密结合。然而，关于ANS在这些相互作用中的荧光特性的数据很少。通过荧光光谱和圆二色光谱研究了ANS与精氨酸和赖氨酸衍生物的结合，以补充通过等温滴定量热法（ITC）获得的已发表信息。赖氨酸和精氨酸的带电基团与ANS的磺酸基团相互作用导致荧光增强且发生蓝移。精氨酸（或赖氨酸）与ANS的磺酸基团之间的离子配对降低了分子间电荷转移（CT）速率常数，从而导致荧光增强。ANS的 - NH基团附近的正电荷改变了分子内电荷转移过程，使荧光发生蓝移。与赖氨酸相比，精氨酸侧链与ANS的 - NH基团和磺酸基团的相互作用更有效。ANS的结合还会诱导多聚精氨酸从无规卷曲向α - 螺旋转变。我们的数据与ITC结果相反，表明ANS衍生物与带正电的侧链之间的静电相互作用并不能解释微摩尔范围内的结合亲和力。对于蛋白质的高亲和力（K - d < 1 mM）外部结合位点，除了离子配对，还应考虑诸如范德华力等互补相互作用。由爱思唯尔公司出版。
8-anilino-1-naphthalenesulfonic acid (ANS) is believed to strongly bind cationic groups of proteins and polyamino acids through ion pair formation. A., paucity of data exists on the fluorescent properties of ANS in these interactions. ANS binding to arginine and lysine derivatives was studied by fluorescence and circular dichroism spectroscopies to augment published information attained by isothermal titration calorimetry (ITC). Fluorescence enhancement with a hypsochromic shift results from the interaction of the charged group of lysine and arginine with the sulfonate group of ANS. Ion pairing between Arg (or Lys) and the sulfonate group of ANS reduce the intermolecular charge transfer (CT) rate constant that leads to enhancement of fluorescence. A positive charge near the -NH group of ANS changes the intramolecular CT process producing a blue shift of fluorescence. The Arg side chain compared to that of Lys more effectively interacts with both the -NH and sulfonate groups of ANS. ANS binding also induces a random coil-alpha helix transition in poly-Arg. Our data, in contrast to ITC results, indicate that electrostatic interactions between ANS derivatives and positively charged side chains do not account for binding affinity in the micromolar range. In addition to ion pairing complementary interactions, such as van der Waals, should be considered for high affinity (K-d < 1 mM) external binding sites of proteins. Published by Elsevier B.V.