1、Chapter 1 Amino Acids, Peptides and Proteins-3-Tertiary and quaternary structuresSummary1、超二級(jí)結(jié)構(gòu)3、蛋白家族2、四級(jí)結(jié)構(gòu)4、蛋白的變性和折疊Tertiary structure: bend-producing residues: Pro, Thr, Ser, and GlyQuaternary structure: two or more separate polypeptide chains, which are identical or different.Fibrous protein: a s

2、ingle type of secondary struture.Globular protein: several types of secondary structure.Analysis of many globular proteins reveals common strutural patterns Supersecondary structures (motifs or simply folds)Particularly stable arrangements of several elements of secondary struture and the conections

3、 between them.Polypeptides with more than a few hundred amino acid residues ofter fold into two or more stable, globular units called domains. It retain its correct 3-D structure even when it is separated from the remainder of the polypeptide chain.1、超二級(jí)結(jié)構(gòu)和三級(jí)結(jié)構(gòu)Burial of hydrophobic amino acid R grou

4、ps so as to exclude water requires at least two layers of secondary structure.helices and sheets generally are found in different structural layers.Connections between elements of secondary structure cannot cross or form knots.Right handedRight handedParallel sheetFound in many enzymesMotifQuaternar

5、y structureMultimerOligomer2、四級(jí)結(jié)構(gòu)Helical symmetry or rotational symmetryPymolSperm whale myoglobinHydrophobic residuesThe hemo groupGlobular protein structureProtein familySignificant promary sequence similaritySimilar structure and functionStrong evolutionary relationshipSuperfamiliesTwo or more fa

6、milies with little primary sequence similarityUse the same structural motif Have functional similarities3、蛋白家族Fibrous protein structureHairGlyStructure of collagenOsteogenesis imperfectaEhlers-Danlos syndromeGly-X-Y repeatStructure of silk or spider webProtein denaturation and foldingDenaturation: l

7、oss of three-dimensional structure sufficient to cause loss of function.Heat, extremes of PH, alcohol, urea and guanidine hydrochloride, or detergents4、蛋白的變性和折疊Protein tertiary structure is determined by amino acid sequenceProtein folding in cells involves multiple pathwaysSecondary structure supersecondary structure single native conformationHsp70 chaperones and chaperoninsFoldingchaperoneschaperoninsProtein disu