Design,Synthesis Based On The Conserved Sequence Of BRCA Gene And Interaction With The Target Of RAD51

Breast cancer is one of the malignant tumors that threaten women's health.With the increase of age,the number of patients continues to increase,and its occurrence involves a variety of gene changes.These changes cause malignant proliferation of cells and induce canceration.The study found that most breast cancer patients are closely related to the mutation of breast cancer susceptibility gene?BRCA?.Breast cancer susceptibility genes BRCA1 and BRCA2 are located on human chromosomes17 and 13,respectively,and are very important tumor suppressor genes.The harmful mutations of BRCA1 and BRCA2 will reduce gene regulation and DNA repair function,leading to the accumulation of damaged DNA and disorder of homologous recombination repair function in the cell,thereby increasing the incidence of breast cancer,ovarian cancer and other cancers.DNA homologous recombinase RAD51 is an important DNA repair protein and a widely studied tumor suppressor gene product.In the process of maintaining the stability and integrity of the genome,homologous recombination can accurately repair the broken DNA double-strand.RAD51 is one of the most important proteins involved in the repair process.The interaction between BRCA1 or BRCA2 and RAD51 plays a key role in homologous recombination and double-stranded DNA repair.In this paper,the conserved sequences in the BRCA?BRCA1 and BRCA2?genes are used as templates,the key peptides of RAD51 are targeted,and 11 mutant peptides that can improve the effect of RAD51 are screened.It was synthesized by Fmoc solid phase synthesis,separated and purified by reverse-phase high-performance liquid chromatography?RP-HPLC?,and finally characterized by electrospray ionization mass spectrometry?ESI-MS?to obtain target peptides with purity above 95%.The interaction between BRCA peptides and RAD51 key peptides were studied by using fluorescence spectroscopy and circular dichroism spectroscopy?CD?.CD results showed that the secondary structure of RAD51 changed after adding any BRCA peptide.Fluorescence spectroscopy results show that there will be different degrees of fluorescence quenching after adding any BRCA-like peptides of different concentrations,and the quenching methods are static quenching after calculation.Combining the two spectral results,it was found that all peptides can independently bind to RAD51,but different peptides have different binding capabilities,including mutant peptides BRCA1?856-871,Y856R,R866Y,Q867R?and BRCA2?1524-1548,V1542R?The interaction with RAD51 is strong,and the binding constants are2.065×10⁴ L·mol^-1 and 3.41×10⁴ L·mol^-1,respectively.