(精选)【医学课件课件大全】蛋白组学教学课件.ppt

Qiang Miao, Dept. of Chem. Chem. Eng., Nanjing Univ. P(1)ij,t = f ij,t / fi*,t *表示任意氨基酸；i, j氨基酸；t二级结构 f ij,t = nij,t / nij 二肽ij中出现二级结构t的几率 f i*,t = ni*,t / ni* 氨基酸i位于N端二肽出现二级结构t的几率 == P(1)ij,t = (nij,t / nij ) / (ni*,t / ni*) = (nij,t / ni*,t) / (nij / ni*) P(2)ij,t = f ij,t / f*j,t = (nij,t / n*j,t) / (nij / n*j) f*j,t = n*j,t / n*j 氨基酸j位于C端二肽出现二级结构t的几率 左、右邻位氨基酸的影响 Hydrogen bonds within proteins Ions in aqueous solutions are surrounded by water molecules Ionic bonds Multiple noncovalent bonds can confer binding specificity Protein structure determines function There are 20 different amino acids A protein’s amino acid sequence determines its three-dimensional structure (conformation) In turn, a protein’s structure determines the function of that protein All amino acids have the same general structure but the side chain (R group) of each is different Hydrophilic amino acids Hydrophobic and “special” amino acids Peptide bonds connect amino acids into linear chains Four levels of structure determine the shape of proteins Primary: the linear sequence of amino acids Secondary: the localized organization of parts of a polypeptide chain (e.g., the ? helix or ? sheet) Tertiary: the overall, three-dimensional arrangement of the polypeptide chain Quaternary: the association of two or more polypeptides into a multi-subunit complex Secondary structure: the ? helix Secondary structure: the beta sheet Primary and secondary structure in hemagglutinin Tertiary and quaternary structure in hemagglutinin Folding of proteins A newly synthesized polypeptide chain must undergo folding and often chemical modification to generate the final protein All molecules of any protein species adopt a single conformation (the native state), which is the most stably folded form of the molecule The information for protein folding is encoded in the sequence X-ray crystallography is used to determine protein structure Other techniques such as cryo