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Functional Molecular Assemblies Coupled to Steric Control with High Enantioselectivity

与空间控制耦合的具有高对映选择性的功能分子组装体

基本信息

批准号：
07650968
负责人：
UEOKA Ryuichi
金额：
$ 1.34万
依托单位：
Kumamoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Enantioselective hydrolysis of amino acid esters by L-histidine derivatives in the molecular assemblies composed of single-and double-chain surfactants was investigated. The noteworthy aspects are as follows :1) The remarkably high enantioselectivity (kappa^L_<a, obsd>/kappa^D_<a, obsd>=1000) was sttained for the hydrolysis of longchained substrate (N-dodecanoyl-D (L) -phenylalanine p-nitrophenylester ; C_<12>-D (L) -Phe-PNP) catalyzed by the active tripeptide (N-(benzyloxycarbonyl) -L-phenylalanyl-L-histidyl-L-leucine ; Z-PheHisLeu) in the coaggregate systems composed of 41mol% single-chained hexadecyltrimethylammonium bromide (CTAB) and 59mol% double-chained ditetradecyldimethylammonium bromide (2C_<14>Br) at the specific ionic strength (mu=0.02).Furthermore, the computer modeling (MOPAC calculation) study suggests that a favorable molecular recognition between the substrate and the catalyst through the effective hydrophobic interactions and hydrogen bonds should be very important for the enhancement of enantioselectivity.2) With respect to the hydrolysis of C_<12>-D (L) -Phe-PNP by the tripeptide catalyst Z-PheHisLeu in the coaggregate systems composed of native lipid and nonionic micellar surfactant, a remarkably high enantioselectivity (kappa^L_<a, obsd>/kappa^D_<a, obsd>=28) along with marked rate-enhancement of the hydrolytic cleavage of C_<12>-D (L) -Phe-PNP was obtained with specific coaggregates of 32mol% L-alpha-dipalmitoylphosphatidyl-choline (DPPC) and 68mol% alpha-[4-(1,1,3,3-tetramethylbutyl) phenyl]-omega-hydroxypoly (exy-1,2-ethanediyl) (Triton X-100). The enantioselectivity was maximized at the phase transition temperature (Te) in the 65mol% DPPC/35mol% Triton X-100 and 32mol% DPPC/68mol% Triton X-100 coaggregate systems. The hydrophobicity and fluidity of the coaggregates can apparently be changed around Te on the basis of isokinetic temperature and fluorescence parameter studies.

研究了L-组氨酸衍生物在由单、双链表面活性剂组成的分子组装体中对氨基酸酯的对映选择性水解。1）活性三肽催化长链底物（N-十二烷酰基-D（L）-苯丙氨酸对硝基苯酯; C_D（L）-Phe-PNP）的水解具有非常高的对映选择性（kappa^L_a，obsd>/kappa^D_a，obsd>=1000<12>（N-（苄氧羰基）-L-苯丙氨酰-L-组氨酰-L-亮氨酸; Z-PheHisLeu）在由41mol%单链十六烷基三甲基溴化铵（CTAB）和59mol%双链状双十四烷基二甲基溴化铵（<14>2C_Br）在特定离子强度下（mu=0.02）。此外，计算机建模（MOPAC计算）研究表明，通过有效的疏水相互作用和氢键，底物和催化剂之间良好的分子识别对于提高对映选择性是非常重要的。在<12>天然脂质和非离子胶束表面活性剂组成的共聚集体体系中，三肽催化剂Z-PheHisLeu对C_-D（L）-Phe-PNP的水解具有很高的对映体选择性（kappa^L_<a，obsd>/kappa^D_<a，obsd>=28），同时沿着明显的水解速率提高<12>。二棕榈酰磷脂酰胆碱（DPPC）和68mol% α-[4-（1，1，3，3-四甲基丁基）苯基]-ω-羟基聚（己基-1，2-乙二基）（Triton X-100）。在65mol%DPPC/35mol%Triton X-100和32mol%DPPC/68mol%Triton X-100共聚集体体系中，在相变温度（Te）下，对映体选择性最大。在等动力学温度和荧光参数研究的基础上，共聚集体的疏水性和流动性可以明显地改变周围Te。