The Synthesis And Interaction Of BRC8-simulated Peptide With P53(117-142)

Cancer is a high-mortality didease. Cancer causes involve changes in varius genes and theirproducts. RAD51and P53are the tumor suppressor genes which are studied widely. Theyfunction properly by the regulating of breast cancer susceptibility gene2(BRCA2). BRCA2isan important anti-oncogene and correlated with many cancers. The repeat unit BRC is theimportant functional areas of BRCA2. BRC interact with p53and RAD51in the cancerationprocess. BRC mutation was observed in lots of breast cancer patient’s bodies. The study ofBRC’s structure and property is useful for designing and synthesizing anti-cancer drugs.In this thesis, two BRC-simulated peptides were designed by replacing Gly with Phe and Cyswith Ser in the structure of BRC8, respectively.(NSSAFSGFCTASGKQVSILESCLHKVKGVLEEFDL, NSSAGSGFCTASGKQVSILESCLHKVKGVLEEGDL). The two BRC-simulatedpeptides and p53were synthesized by solid phase and the segment connection method.(p53：GTAKSVTCTYSPALNKMFCQLAKTCP). The BRC8was synthesized by fragmentcondensation method. All peptides were purified by RP-HPLC, and charactered by ESI-MS.The interaction of three BRC peptidomimetics with p53had been investigated by usingultraviolet visible absorption spectrometry (UV-Vis), fluorescence spectroscopy and circulardichroism spectrum. The results showed that: With the increasing of BRC8peptide andNSSAFSGFCTASGKQVSILESCLHKVKGVLEEFDL’s concentration, the absorption spectra ofp53showed hyperchromicity. But, it showed hypochromicity with increasing the concentrationof NSSAGSGFCTASGKQVSILESCLHKVKGVLEEGDL. The fluorescence intensity of p53increased at first and then decreased with increasing the concentration of BRC8andNSSAFSGFCTASGKQVSILESCLHKVKGVLEEFDL. But with the increasing of NSSAGSGFCTASGKQVSILESCLHKVKGVLEEGDL’s concentration, the fluorescence intensity of p53increased firstly and then decreased. From above experimental results, it can be concluded thatPhe had very important effect on the interaction of BRC8with p53. The results of circular dichroism show that the content of β-sheet of p53is17％. After the interaction between p53andthree kinds of BRC peptides, the content of β-sheet of p53increased to20％、22％and26％,respectively.