Syntheses Of 867 Mutant Analog BRCA1(846-871)Peptides And Interaction Of They With RAD51

BRCA1 is an important tumor suppressor gene that can be involved in a variety of biological activities.RAD51 is a protease which involved in DNA damage repair by homologous recombination.It has been proved that cancer would be inhibited by the interaction of BRCA1 and RAD51in vivo.The interaction of BRCA1(846-871)and RAD51(158-180)?RAD51(181-200)were investigated in this article.Based on the structure of BRCA1(846-871)and RAD51,the mutations of 867 glutamine in BRCA1(846-871)were designed.Then,14 single-mutant peptides which showed the better interaction activity were selected for further research.A series of polypeptides including BRCA1(846-871)?RAD51(158-180)?RAD51(181-200)and 14 single-mutant peptides were synthesized by solid phase synthesis,purified by HPLC and characterized by ESI-MS.Finally,17 peptides with purity greater than 90%were gotten.The interaction of BRCA1(846-871)peptide with RAD51 were investigated by using circular dichromatogram and fluorescence spectra.Analog BRCA1(846-871)peptides were added to the target peptide RAD51(158-180)and RAD51(181-200),the signal of circular dichromatogram and fluorescence spectra were changed for RAD51.By fluorescence calculation,the static quenching of BRCA1 peptide and RAD51 peptide was obtained,the sign of that indicated the two had strong interaction,the binding site and binding constant were calculated.The results of fluorescence showed that the binding constant of 867Q changed to Y was maximum,867Q/C,867Q/R,867Q/T were weaker than it relatively,and the binding constant of 867Q changed to V was minimum,compared with the fluorescence of BRCA1(846-871,867 Q).It has been shown that the secondary structure of the mutated amino acid residues was higher than unmutated BRCA1(846-871)by analyzing CD results.Meanwhile,the a-helix of BRCA1(846-871,867Q/Y)was higer than others.The CD results were consentience with fluorescence results.