Disulfide bonds yog ib feem tseem ceeb ntawm cov qauv peb-dimensional ntawm ntau cov proteins.Covalent bonds tuaj yeem pom nyob rau hauv yuav luag tag nrho cov peptides extracellular thiab protein molecules.
Ib daim ntawv cog lus disulfide yog tsim thaum lub cysteine sulfur atom tsim ib qho kev sib cog lus nrog rau lwm ib nrab ntawm cystine sulfur atom ntawm ntau txoj haujlwm hauv cov protein.Cov ntawv cog lus no pab kom ruaj khov ntawm cov protein, tshwj xeeb tshaj yog cov uas zais los ntawm cov hlwb.
Kev tsim kom muaj txiaj ntsig zoo ntawm cov ntawv cog lus disulfide muaj ntau yam xws li kev tswj xyuas cov cysteine kom zoo, kev tiv thaiv cov amino acid residues, kev tshem tawm cov pab pawg tiv thaiv, thiab kev sib koom ua ke.
Peptides tau grafted nrog disulfide bonds
Gutuo kab mob muaj ib tug paub tab disulfide daim ntawv cog lus nplhaib tshuab.Yog tias peptide tsuas muaj ib khub Cys, qhov kev tsim cov nyiaj disulfide yog ncaj nraim.Peptides yog synthesized nyob rau hauv cov khoom los yog kua theem,
Tom qab ntawd nws tau oxidized hauv pH8-9 kua.Lub synthesis yog qhov nyuaj thaum ob los yog ntau dua khub ntawm disulfide bonds yuav tsum tau tsim.Txawm hais tias disulfide daim ntawv cog lus feem ntau ua tiav lig hauv cov txheej txheem hluavtaws, qee zaum kev qhia txog cov khoom siv ua ntej yog qhov zoo rau kev sib txuas lossis elongating peptide chains.Bzl yog Cys tiv thaiv pab pawg, Meb, Mob, tBu, Trt, Tmob, TMTr, Acm, Npys, thiab lwm yam, siv dav hauv symbiont.Peb tshwj xeeb hauv disulphide peptide synthesis suav nrog:
1. Ob khub ntawm disulfide bonds yog tsim nyob rau hauv lub molecule thiab ob khub ntawm disulfide bonds yog tsim nyob rau hauv lub molecules
2. Peb khub ntawm disulfide bonds yog tsim nyob rau hauv lub molecule thiab peb khub ntawm disulfide bonds yog tsim nyob rau hauv lub molecules
3. Insulin polypeptide synthesis, qhov twg ob khub ntawm disulfide bonds yog tsim los ntawm txawv peptide sequences
4. Synthesis ntawm peb khub ntawm disulfide-bonded peptides
Vim li cas cysteyl amino pawg (Cys) thiaj li tshwj xeeb?
Lub sab saw ntawm Cys muaj ib pab pawg neeg reactive heev.Cov hydrogen atoms hauv pab pawg no tau yooj yim hloov los ntawm cov dawb radicals thiab lwm pab pawg, thiab yog li tuaj yeem yooj yim tsim covalent bonds nrog lwm cov molecules.
Disulfide bonds yog ib feem tseem ceeb ntawm 3D qauv ntawm ntau cov proteins.Disulphide choj daim ntawv cog lus tuaj yeem txo qhov elasticity ntawm peptide, nce qhov tawv nqaij, thiab txo cov duab muaj peev xwm.Qhov kev txwv cov duab no yog qhov tseem ceeb rau kev ua haujlwm lom neeg thiab cov qauv kev ruaj ntseg.Nws qhov kev hloov pauv yuav ua rau muaj kev cuam tshuam rau tag nrho cov qauv ntawm cov protein.Hydrophobic amino acids xws li Dew, Ile, Val yog helix stabilizer.Vim tias nws stabilizes disulfide-bond α-helix ntawm cysteine tsim txawm tias cysteine tsis tsim disulfide bonds.Qhov ntawd yog, yog tias tag nrho cov cysteine residues nyob rau hauv lub xeev txo, (-SH, nqa dawb sulfhydryl pawg), feem pua ntawm cov helical feem ntau yuav ua tau.
Cov disulfide bonds tsim los ntawm cysteine yog ruaj khov rau kev ruaj ntseg ntawm cov qauv tertiary.Feem ntau, SS Bridges ntawm daim ntawv cog lus yog tsim nyog rau kev tsim cov qauv quaternary.Qee zaum cov cysteine residues uas tsim cov ntawv cog lus disulfide nyob deb ntawm cov qauv thawj.Lub topology ntawm disulfide bonds yog lub hauv paus rau kev tsom xam ntawm protein thawj qauv homology.Cov cysteine residues ntawm homologous proteins yog heev txuag.Tsuas yog tryptophan tau suav nrog kev txuag ntau dua li cysteine.
Lub cysteine yog nyob rau hauv nruab nrab ntawm lub catalytic site ntawm thiolase.Cysteine tuaj yeem tsim acyl intermediates ncaj qha nrog cov substrate.Daim ntawv txo qis ua raws li "sulfur buffer" uas khaws cov cysteine hauv cov protein hauv lub xeev txo.Thaum pH qis, qhov sib npaug txaus siab rau qhov txo qis -SH daim ntawv, thaum nyob rau hauv alkaline ib puag ncig -SH yog ntau yooj yim rau oxidized rau daim -SR, thiab R yog dab tsi tab sis ib tug hydrogen atom.
Cysteine kuj tuaj yeem hnov mob nrog hydrogen peroxide thiab organic peroxides ua cov tshuaj lom.
Post lub sij hawm: May-19-2023