| Breast cancer susceptibility gene2(BRCA2) is a tumor suppressor gene, it’s related todifferent cancers, such as breast, ovarian, pancreatic cancer. Human RAD51protein, thehomologous of Escherichia coli RecA, plays a crucial role in homologous recombination. TheBRCA2protein contains eight conserved BRC repeat motifs (BRC1~BRC8) of about35amino acids each. In vivo, BRCA2interacts directly with RAD51, and controls the loadingand removal of RAD51by means of the eight BRC motifs during the DNA repair process, butthe precise reaction mechanism is not yet clear.Because of the large size of BRCA2and RAD51protein, it’s difficult to obtain thefull-length purified proteins to be used for research, and therefore, it’s a convenient way toinvestigate the interaction effects of BRC function motifs with RAD51peptide fragments.Particularly, human BRC4motif contains all of the consensus sequence, promotes theassembly of RAD51protein filament on single-stranded DNA and shows stronger binding tohuman RAD51than the other BRC repeats. So BRC4motif was served as a template peptide,and a serious of BRC4-like peptides (BRC4-3, BRC4-5, BRC4-6, BRC4-7, BRC4-8, BRC4-9,BRC4-10) were designed, according to the three dimensional (3D) crystal structure of thehuman BRC4-RAD51complex. In addition, RAD51(191-220) fragment was chose to be as atarget peptide. In the end, BRC4peptide, six BRC4-like peptides and RAD51(191-220)fragment peptide were synthesized using Wang resin following Fmoc-strategy and with thestandard peptide HBTU/HOBT/DIEA coupling reagents. The crude peptides were purified byRP-HPLC and identified by ESI-MS. The results showed that the peptides with over90%purity were achieved and the m/z values were consistent with their theoretical molecularweights.Experiment results indicate that it’s a viable option to stepwise solid-phase peptidesynthesis for synthesizing long chain peptides. It’s necessary to investigate the molecularmechanisms of BRCA2and RAD51protein in the next step. |
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