关键词: 芽孢杆菌，炭疽;配体;亲和力

    摘 要:目的 研究炭疽芽孢适配子结构与长度变化对其与芽孢之间亲和力的影响. 方法 人工合成f77-1适配子序列，并构建在其7条突变体序列，将这些寡核苷酸序列分别与炭疽芽孢结合，利用TMB显色系统判断读取吸光度A值，确定各序列与芽孢间亲和力大小;同时通过核酸序列分析软件包模拟各序列的二级结构，推断适配子的结构与亲和力之间的关系. 结果 适配子f77-1与突变体中的f77-3与芽孢亲和力较好，约是突变体中f77-4亲和力的11倍，二级结构显示:f77-1，f77-3都具有茎环或发卡结构，且3'端都有连续3个G. 结论 适配子5'端的茎环结构和发卡结构是这些寡核苷酸序列与芽孢结合的结构基础，3'端的连续3个G可能对提高亲和力起着重要的作用.

    Relationship between the secondary structure of an aptamer and its binding affinity to Bacillus anthracis spores

    ZHEN Pei SONG Ya-Jun GUO Zhao-Biao WANG Jin YU Shou-Yi YANG Rui-Fu

    1 Department of Epidemiology，First Military Medi-cal University，Guangzhou510515，China，

    2 Laboratory of Analytical Microbiology，National Center of Biomedical Analysis，Institute of Microbi-ology&Epidemiology，Academy of Military Medi-cal Sciences，Beijing100071，China

    Keywords:Bacillus anthracis;ligands;affinity

    Abstract:AIM To determine the effects of aptamers length and structure on its binding affinity to spores of Bacillus an-thracis vaccine strain A.16R.METHODS An oligonu-cleotide aptamer f77-1and its seven mutants were synthe-sized.Binding of oligonucleotides to spores was visualized by biotin-streptavidin-horseradish peroxides system.All theo-retical secondary structures were caculated using the Fold subroutine of the DNASIS v2.5software package based on a free energy minimization algorithm.RESULTS Affinities of the aptamer f77-1and mutant f77-3were11times higher than that of mutant f77-4.And the theoretical secondary structures calculated showed that they had stem-loop or hair-pin at5'end of the aptamer and mutant and GGG sequences at3'end of the structures.CONCLUSION Stem-loop and hairpin at5'end of the aptamer work as main motif in the in-teraction between oligonucleotides and spores.Meanwhile ......