2017 peptidebond(1).pptxVIP免费

Proteins王春光2017-09-21chunguangwang@tongji.edu.cn220commonaminoacids3D-,L-stereoisomers（立体异构体）Opticalabsorbance（光吸收）pI(isoelectricpoint)（等电点）Otheraminoacidsandpost-translationalmodifications（翻译后修饰）Somethingtoknowaboutaminoacids4OnlytheL-formofaminoacidsareusedtobuildproteins.Aminoacids,exceptglycine,arechiral（手性的）.5678(Lambert-Beerlaw)Opticalabsorbance（光吸收）9OD280forproteinquantification10Afewexamplesofotheraminoacids11Peptidebond肽键12Ser-Gly-Tyr-Ala-LeuLeu-Ala-Tyr-Gly-SerMainchain（主链）vs.sidechain（侧链）SGYALLAYGS13Aminoacidvs.residue(残基).OHH1415SomesmallpeptidesofphysiologicalinterestAspartame:methylesterderivativeofL-Aspartyl-L-phenylalanine;200xsweeterthansugar.16SomesmallpeptidesofphysiologicalinterestGlutathione(GSH)（谷胱甘肽）:tripeptidescavengerofoxidizingagents;oxidizedformconsistsoftwoglutathionemoleculesjoinedbydisulfidebridge.17insulin胰岛素18FrederickSangerTheNobelPrizeinChemistry1980TheNobelPrizeinChemistry1958"forhisworkonthestructureofproteins,especiallythatofinsulin""fortheircontributionsconcerningthedeterminationofbasesequencesinnucleicacids"19NobelPrizeinChemistry1964"forherdeterminationsbyX-raytechniquesofthestructuresofimportantbiochemicalsubstances".DorothyCrowfootHodgkinInsulinstructure2021Numberofnegativelychargedresidues(Asp+Glu):9Numberofpositivelychargedresidues(Arg+Lys):17Lysozyme溶菌酶Primarysequenceof129residues:KVFGRCELAAAMKRHGLDNYRGYSLGNWVCAAKFESNFNTQATNRNTDGSTDYGILQINSRWWCNDGRTPGSRNLCNIPCSALLSSDITASVNCAKKIVSDGNGMNAWVAWRNRCKGTDVQAWIRGCRLTheoreticalpI:9.32(http://web.expasy.org/cgi-bin/protparam/protparam)22a-helixb-sheetLysozymestructure(PDB3LYM)23Ana-helixinlysozyme:RCELAAAMKRH(colorcode:CNO)24Theahelix•Tomakeoptimaluseofinternalhydrogenbonds.•Everyhelicalturnextendsabout5.4Åalongtheaxis.•Onlyright-handedhelix.•Everyhelicalturnincludes3.6residues,sothateveryresidueturns100degrees.5.4Å25Interactionbetweensidechainsofresidueiandi+3ori+4;Prorarelyappearsina-helix.Ana-helixinl...