Groups with polar characteristics can locate at both shallow and deep locations in membranes: The behavior of dansyl and related probes
Groups with polar characteristics can locate at both shallow and deep locations in membranes: The behavior of dansyl and related probes
复制标题
DOI：
10.1021/bi9726234
复制
发表时间：
1998-03-31
期刊：
影响因子：
2.9
通讯作者：
London, E
中科院分区：
文献类型：
--
作者：
Asuncion-Punzalan, E;Kachel, K;London, E
为了了解极性分子的化学结构和它们的膜位置之间的关系，检测了丹磺酰基（二甲基氨基萘磺酰基）和相关极性荧光探针的行为。这些探针在脂质双层中的深度通过荧光猝灭的视差分析来确定[Chattopadhyay和伦敦（1987）生物化学26，39-45; Abrams和伦敦，生物化学（1993）32，10826-10831]。测量丹磺酰基的猝灭：（1）连接到PE的极性头基，（2）连接到烷基链，（3）连接到脂肪酰基链的末端，和（4）通过间隔基团连接到PE的极性头基。在所有情况下，丹磺酰基探针位于极性头基区域，距离双层中心19-21埃。这表明丹磺酰基具有在极性头基区域中寻找浅位置的强烈倾向。这种模式的唯一例外是在二烷基化丹磺酰基的情况下，观察到两个群体。一个人口是在极性头基水平，但第二个是深埋在酰基链区域。为了观察丹磺酰基的极性磺酰胺基团是否影响深度，合成了取代硫代氨基甲酰基连接的结构相关的探针，二甲基氨基萘硫代氨基甲酰基（dantyl）标记的PE。丹酰基团位于比丹酰基团更深的位置，距离双层中心13-16埃。丹磺酰基和曼恩磺酰基（甲基苯胺基萘磺酰基）衍生物之间的深度差异甚至更大。Mansyl探针，它有一个额外的苯基相对于丹磺酰基，被发现位于深内的酰基链区域的双层（6-7埃从双层中心）时，连接到PE的极性头基。因此，极性基团的膜位置强烈地依赖于它们的化学结构的细节，并且极性基团可能位于浅位置和深位置。这些结果表明，在双层的疏水部分中掩埋极性部分的能量并不过高。这与带电基团的行为形成对比，带电基团似乎仅限于膜中的浅位置。在本报告中，还考虑了两个不同深度处的人口对视差分析的影响。
To understand the relationship between the chemical structure of polar molecules and their membrane location, the behavior of dansyl (dimethylaminonaphthalenesulfonyl) and related polar fluorescent probes was examined. The depth of these probes in lipid bilayers was determined by parallax analysis of fluorescence quenching [Chattopadhyay and London (1987) Biochemistry 26, 39-45; Abrams & London, Biochemistry (1993) 32, 10826-10831]. Quenching was measured for dansyl groups: (1) attached to the polar headgroup of PE, (2) linked to an alkyl chain, (3) attached to the end of a fatty acyl chain, and (4) attached to the polar headgroup of PE via a spacer group. In all cases, the dansyl probes located in the polar headgroup region, 19-21 Angstrom from the bilayer center. This shows the dansyl group has a strong tendency to seek a shallow location in the polar headgroup region. The only exception to this pattern was in the case of a dialkylated dansyl, for which two populations were observed. One population was at the polar headgroup level, but the second was deeply buried in the acyl chain region. To see if the polar sulfonamide group of dansyl influences depth, a structurally related probe substituting a thiocarbamoyl linkage, dimethylaminonaphthalenethiocarbamoyl (dantyl)-labeled PE, was synthesized. Dantyl groups were located deeper than dansyl groups, 13-16 Angstrom from the bilayer center. There was an even more dramatic difference in depth between dansyl and mansyl (methylanilinonaphthalenesulfonyl) derivatives. Mansyl probes, which have an extra phenyl group relative to dansyl, were found to locate deeply within the acyl chain region of the bilayer (6-7 Angstrom from the bilayer center) when attached to the polar headgroup of PE. Thus, the membrane location of polar groups depends strongly on the details of their chemical structure, and it is possible for a polar group to locate both at shallow and deep locations. These results suggest the energy to bury a polar moiety in the hydrophobic part of the bilayer is not prohibitively high. This contrasts to the behavior of charged groups, which appear to be restricted to shallow locations in membranes. In this report, the effect of populations at two different depths on the parallax analysis is also considered.