Secondary Structural Preferences of Some Antibacterial Cyclooctapeptides in the Presence of Calcium(II).
Secondary Structural Preferences of Some Antibacterial Cyclooctapeptides in the Presence of Calcium(II).
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钙 (II) 存在下某些抗菌环八肽的二级结构偏好。
DOI：
10.1155/2012/730239
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发表时间：
2012
影响因子：
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通讯作者：
Ngu-Schwemlein,Maria
中科院分区：
文献类型：
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作者：
Stevens,Tarshona;McNeil,Nykia;Lin,Xiuli;Ngu-Schwemlein,Maria
本研究的目的是了解一些抗菌阳离子两亲性环八肽与钙（II）的相互作用及其二级结构偏好。通过等温滴定量热法研究了具有抗菌活性的环八肽（COP 1-6）和那些没有表现出显着活性的环八肽（COP 7-9）之间与钙（II）相互作用相关的热力学参数。用圆二色性（CD）研究了十二烷基磷酸胆碱（DPC）胶束对钙离子结合的影响。两组环肽都显示出对钙（II）的弱结合亲和力（Kbca. 10−3M−1）。然而，CD数据显示，抗菌肽COP 1- 6采用扭曲的β折叠结构（正CD吸收带at ca. 203 nm）的胶束DPC中的钙（II）的存在下。相反，缺乏抗菌活性的COP 7-9采用了不同的构象结构（负CD吸收带atca. 203 nm）。这些结果表明，这些环肽可以采取二级结构的偏好，在钙（II）的存在下，在疏水环境中，以引起其抗菌活性。这些发现可能有助于促进可以采用这种β折叠样二级结构的环肽衍生物的设计，从而为制备抗菌化合物提供有用的分子模板。
The purpose of this study is to understand the interactions of some antibacterial cationic amphipathic cyclooctapeptides with calcium(II) and their secondary structural preferences. The thermodynamic parameters associated with calcium(II) interactions, between the antibacterial active cyclooctapeptides (COP 1–6) and those that did not exhibit significant activities (COP 7–9), were studied by isothermal titration calorimetry. Calcium(II) binding in the absence and presence of micellar dodecylphosphocholine (DPC), a membrane mimicking detergent, was conducted by circular dichroism (CD). Both groups of cyclopeptides showed weak binding affinities for calcium(II) (Kbca. 10−3M−1). However, CD data showed that the antimicrobial peptidesCOP 1–6adopted a twisted beta‐sheet structure (positive CD absorption band atca. 203 nm) in the presence of calcium(II) in micellar DPC. In contrast,COP 7–9, which lacked antibacterial activity, adopted a different conformational structure (negative CD absorption band atca. 203 nm). These results indicate that these cyclopeptides could adopt secondary structural preferences in the presence of calcium(II) amidst a hydrophobic environment to elicit their antibacterial activity. These findings could be useful in facilitating the design of cyclopeptide derivatives that can adopt this beta‐sheet‐like secondary structure and, thereby, provide a useful molecular template for crafting antibacterial compounds.