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961.
Structure‐guided RP‐HPLC chromatography of diastereomeric α‐helical peptide analogs substituted with single amino acid stereoisomers 下载免费PDF全文
YiBing Huang Ling Pan LianJing Zhao Colin T. Mant Robert S. Hodges Yuxin Chen 《Biomedical chromatography : BMC》2014,28(4):511-517
An α‐helical model peptide (Ac‐EAEKAAKE‐X‐EKAAKEAEK‐amide) was used as a template to examine the efficacy of conventional reversed‐phase high‐performance liquid chromatography (RP‐HPLC) in separating peptide analogs with single substitutions (at position X) of diasteromeric amino acids Ile, allo‐Ile, d ‐Ile and d ‐allo‐Ile. We compared differences in peptide retention behavior on a C8 column and a C18 column at different temperatures. We demonstrated how subtle differences in peptide secondary structure affected by the different substitutions of amino acids with identical overall hydrophobicity enabled effective resolution of these peptide analogs. We also demonstrated the ability of RP‐HPLC to separate Ile‐ and allo‐Ile‐substituted analogs of a 26‐residue α‐helical antimicrobial peptide (AMP), with the substitution site towards the C‐terminus of the α‐helix. These peptides show different values of antibacterial activity and hemolytic activity, and different selectivity against bacteria and human cells. Our results underline the ability of RP‐HPLC to resolve even difficult diasteromeric peptide mixtures as well as its value in monitoring very subtle hydrophobicity changes in de novo‐designed AMP. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
962.
963.
以间苯三酚为起始原料,在伊顿试剂的催化作用下,与不同取代水杨酸反应合成1,3-二羟基呫吨酮类化合物3a~3l 12个,收率63%~87%,并探讨了反应机理及结构-反应活性关系.利用紫外分光光度法测定了所合成化合物对亚硝酸盐的清除作用,结果表明,在37℃、pH 3及反应时间为30 min条件下,1,3-呫吨酮类化合物对亚硝酸根均有较好的清除作用,其中化合物3f和3b的清除作用最强,清除率达34%.同时对1,3-二羟基呫吨酮类化合物清除亚硝酸盐的作用机制及构效关系进行了探讨. 相似文献
964.
H2S is considered as the main gas pollutant from livestock farm and activated carbon (AC) is widely used as adsorbent for H2S. This paper focuses on the influence of modification conditions and operation conditions on the H2S adsorption performance on AC samples. The H2S adsorption performance on modified AC (MAC) samples by single and combinatory method has been investigated. It is concluded that the MAC by combinatory method of high-pressure hydrothermal method followed by alkaline solution impregnation method could promote the H2S adsorption performance remarkably. The H2S adsorption performance differs with different operation conditions. Meanwhile the samples of fresh AC and exhausted AC have been characterized using BET, FTIR, TPD and Boehm titration method. The experimental results are confirmed that the characteristics of AC have significant influence on the adsorption ability for H2S. 相似文献
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966.
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968.
Triterpenoids from the Roots and Stems of Rubus alceaefolius 总被引:1,自引:0,他引:1
969.
Wenjin Zheng Chen Huang Changhe Zhang Yi-Feng Zhou Ji-Dong Lou 《Research on Chemical Intermediates》2013,39(2):499-504
A simple, rapid, and efficient oxidation of oximes to the corresponding ketones and aldehydes with manganese dioxide catalyzed by kieselguhr under solvent-free conditions at room temperature in the yields between 82 and 98 is described. It seems that kieselguhr in the present procedure can highly expedite the reaction rate. By comparing to other methods described previously, the main advantages of this oxidation are that the oxidations are more efficient, the reaction conditions are milder, the reaction times are shorter, and the work-up is easier. Furthermore, the amount of manganese dioxide used in this oxidation is largely decreased. 相似文献
970.
The paper presents and discusses a generalization of the equations of laser-induced circular dichroism (LICD) derived for linear molecules. LICD for freely rotating molecules by a resonant circularly-polarized pump field is an optical analogue of the Faraday effect in isotropic media. Its fundamental formulae and existent conditions have been deduced using the density matrix theory with a two-level model and time-reversal arguments. The antisymmetric rotational polarizability and LICD of symmetric and asymmetric top molecules are studied concretely using perturbation theory and angular momentum algebra. The order of magnitude of LICD and the physical phenomena closely related with it have been discussed. The results show that the LICD effect is exhibited by all freely rotating molecules and may provide useful information on optical activity and antisymmetric polarizability. 相似文献