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POLYPEPTIDE STRUCTURE AND DYNAMICS CONTROLLED BY PHOT0-ISOMERIZATION

光异构化控制的多肽结构和动力学

基本信息

批准号：
10650875
负责人：
HIRAOKI Toshifumi
金额：
$ 2.05万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In order to clarify the mechanism of the helix-sense inversion of poly(β-n-propyl L-aspartate)(PnPLA), the conformational transition of PnPLA and its derivative with azobenzene group were investigated by means of NMR.1) The right-handed α-helix (αィイD2RィエD2)of PnPLA can change thermoreversibly to the left-handed (αィイD2LィエD2) with increasing temperature from 30 to 70℃ in CDClィイD23ィエD2. The midpoint is 50℃, the transition free energy is 110 kJ/mol, and the exchange rate between both conformations is 5 /s at about 50℃. All the ィイD113ィエD1C signals of PnPLA can separate completely between the right- and left-helices, although only the NH and βィイD2sィエD2 proton resonances show the conformational dependence. These results indicate that the side-chain conformation of αィイD2RィエD2-helical PnPLA is different from that of αィイD2LィエD2-helix, as well as the main chain conformation. The αィイD2RィエD2-helix conformation of PnPLA changes to the left-handed, and subsequently to the random-coil with increasing the trifluoroacetic acid concentration. The coil conformation of PnPLA can change to the αィイD2LィエD2-helix with increasing the temperature, and the αィイD2RィエD2-helix is not detected in the high temperatures.2) PnPLA containing 30% p-phenylazobenzene group in the side chain do not show the helix-sense inversion with the photo-isomerization of azobenzene group. The PnPLA containing more than 50% p-phenylazobenzene group is preparing for further experiments.3) The internal rotational angle from the spin-spin coupling constant ィイD13ィエD1Jαβ is necessary to determine the side chain conformation. The monomer of L-asp-βィイD2RィエD2-d was successfully synthesized from the fumaric acid in DィイD22ィエD2O/NDィイD24ィエD2OD with the enzyme of L-aspartase to remove the contribution of the residual geminal ィイD12ィエD1Jββ in the signal of βィイD2sィエD2 proton. PnPLA-βィイD2RィエD2-d is preparing for further experiments.

为了澄清机制helix-sense反演的聚(β-n-propyl L-aspartate) (PnPLA)的构象转变PnPLA及其导数与偶氮苯组研究通过NMR.1)右手α螺旋(αィイD2RィエD2)的PnPLA可以改变thermoreversibly左撇子(αィイ网站ィエD2)随着温度从30到70℃CDClィイc15ィエD2。中点为50℃，过渡自由能为110 kJ/mol，在50℃左右，两种构象的交换速率为5 /s。所有ィイD113ィエD1C信号之间的PnPLA完全可以单独对left-helices,尽管只有NH和βィイD2ィエD2质子共振构象的依赖。这些结果表明，α γ γ γ γ - D2R - γ - D2R - γ -螺旋型PnPLA的侧链构象与α γ - D2L - γ -螺旋型PnPLA的主链构象不同。的αィイD2RィエD2-helix构象PnPLA更改左撇子,随后的无规卷曲与三氟乙酸的浓度增加。随着温度的升高，PnPLA的螺旋构象变为α γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ。2)在侧链中含有30%对苯基偶氮苯基的PnPLA在偶氮苯基光异构化过程中不发生螺旋反转。对苯基偶苯基团含量超过50%的PnPLA正在为进一步的实验做准备。3)内部旋转角的自旋自旋耦合常数ィイD13ィエD1Jαβ确定侧链构象是必要的。利用l -天冬氨酸酶的酶解，成功地以D′′′D22′′D2O/ND′′D24′′D2OD中的富马酸为原料合成了L-asp′-β′′D2R′- D2R′- D2- D单体，以去除β′′D2s′- d1j′ββ对β′′D2s′- d1j′β质子信号的贡献。PnPLA-β φ φ D2R φ φ D2-d正在为进一步的实验做准备。