Craik David J, Cemazar Masa, Wang Conan K L, Daly Norelle L
Institute for Molecular Bioscience and Australian Research Council Special Research Centre for Functional and Applied Genomics, University of Queensland, Brisbane.
Biopolymers. 2006;84(3):250-66. doi: 10.1002/bip.20451.
The cyclotides are a recently discovered family of miniproteins that contain a head-to-tail cyclized backbone and a knotted arrangement of disulfide bonds. They are approximately 30 amino acids in size and are present in high abundance in plants from the Violaceae, Rubiaceae, and Cucurbitaceae families, with individual plants containing a suite of up to 100 cyclotides. They have a diverse range of biological activities, including uterotonic, anti-HIV, antitumor, and antimicrobial activities, although their natural function is likely that of defending their host plants from pathogens and pests. This review focuses on the structural aspects of cyclotides, which may be thought of as a natural combinatorial peptide template in which a wide range of amino acids is displayed on a compact molecular core made up of the cyclic cystine knot structural motif. Cyclotides are exceptionally stable and are resistant to denaturation via thermal, chemical, or enzymatic treatments. The structural features that contribute to their remarkable stability are described in this review.
环肽是最近发现的一类微型蛋白质，其具有头尾相连的环化主链和二硫键的纽结排列。它们大小约为30个氨基酸，在堇菜科、茜草科和葫芦科植物中大量存在，个别植物含有多达100种环肽。它们具有多种生物活性，包括子宫收缩、抗HIV、抗肿瘤和抗菌活性，尽管其天然功能可能是保护宿主植物免受病原体和害虫侵害。本综述聚焦于环肽的结构方面，环肽可被视为一种天然组合肽模板，其中多种氨基酸展示在由环胱氨酸结结构基序构成的紧密分子核心上。环肽异常稳定，能抵抗热、化学或酶处理引起的变性。本综述描述了有助于其显著稳定性的结构特征。
