| Malignant tumor is a disease of harming human health severely, but the treatment of malignant tumor have stayed on radiotherapy, chemotherapy, operation, medicamentum and other conventional methods for years now, which does not make fundamental progress. In recent years, the medical community has turned the target to extract anticancer substances from natural plants, which becomes a hot spot in the field of tumortherapy gradually.β-momorcharin is extracted from bitter melon and substantially is a ribosome-inactivating protein (RIP), and theβ-momorcharin inhibits the biosynthesis of protein by modifying ribosome large-subunit rRNA and further has activity of damaging DNA topology so as to involve in regulating immunodeficiency.The subject researchesβ-momorcharin extracted from plants and determines the protein sequence thereof and the correlated protein properties; it analyses the protein sequence ofβ-momorcharin on all sides by bioinformatics software and on-line bioinformatics websites, models a secondary structure ofβ-momorcharin, and analyses and predicts various restrictive epitopes and possible function binding sites, which serves as the theoretical basis for the clinical application ofβ-momorcharin.The research content is divided into two parts: the first part comprises separating and extractingβ-momorcharin and sequencing and analyzing the property of protein thereof, which specifically comprises: 1, separating and extractingβ-momorcharin through a series of methods of lixiviation in normal saline, fractional precipitation by acetone, ion-exchange column chromatography by CM-Sepharose, gel filtration chromatography by Sephadex G-100, after dialyzing, concentrating and freeze-drying it, obtainingβ-momorcharin with uniform composition; 2, determining the sequence of protein: determining the complete sequence ofβ-momorcharin by acid hydrolysis, basic hydrolysis, computer sequencing and other methods; 3, determining property of protein: determining molecular weight ofβ-momorcharin by a SDS-PAGE method; determining the saccharinity thereof by a phenol-sulfuric acid method; determining isoelectric point by an IEF method; the second part comprises analyzing the structure ofβ-momorcharin and predicting the epitope thereof by a bioinformatics method, which specifically comprises modeling a secondary structure ofβ-momorcharin by employing software DNAStar Lasergene7 or SwissPdb Viewer and the correlated on-line servers, predicting the signal peptide of protein sequence ofβ-momorcharin, B-cell epitopes, CTL epitopes, HLA restrictive CTL epitopes binding force and MHC-I or II molecular combined peptide.The results show that theβ-momorcharin is 32085.2 in molecular weight of protein, 1.3% in saccharinity, and pI9.1 in isoelectric point; there is signal peptide composed of 23 amino acids on an initial extremity ofβ-momorcharin; 6 B-cell epitopes and 3 CTL epitopes are distributed; the HLA restrictive CTL epitope binding force of the sequences 71-79 is high; the three sections share the MHC-I molecular combined peptide, while the two sections share the MHC II molecular combined peptide.Through extracting, sequencing and predicting property and analyzing theβ-momorcharin by the bioinformatics method, modeling a spatial structure thereof, and predicting B-cell antigen site, HLA antigenic peptide and MHC combined peptide, it provides use for reference and reference suggestions for researching into exact biological function of theβ-momorcharin on the molecular level in next step, the immunoregulation process and explaining the anticancer mechanism thereof, and gives help to widen the clinical application.
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