Amabhondi e-disulfide ayingxenye ebalulekile yesakhiwo esinezinhlangothi ezintathu samaprotheni amaningi.Lezi zibopho eziqinile zingatholakala cishe kuwo wonke ama-peptide angaphandle kwamaseli nama-molecule wamaprotheni.
Isibopho se-disulfide senziwa lapho i-athomu yesulfure ye-cysteine yakha isibopho esisodwa esihlangene nengxenye ye-athomu yesulfure ye-cystine ezindaweni ezahlukene kuphrotheni.Lezi zibopho zisiza ukuzinzisa amaprotheni, ikakhulukazi lawo afihliwe kumaseli.
Ukwakhiwa okuphumelelayo kwezibopho ze-disulfide kuhilela izici eziningana ezifana nokuphathwa kahle kwama-cysteines, ukuvikelwa kwezinsalela ze-amino acid, izindlela zokususa zamaqembu okuzivikela, nezindlela zokumatanisa.
Ama-peptides axhunyelelwa ngamabhondi e-disulfide
I-Gutuo organism inobuchwepheshe obuvuthiwe bendandatho yebhondi ye-disulfide.Uma i-peptide iqukethe ipheya eyodwa ye-Cys, ukwakheka kwebhondi ye-disulfide kuqondile.Ama-peptides ahlanganiswa ngezigaba eziqinile noma eziwuketshezi,
Yabe isifakwa i-oxidized kusisombululo se-pH8-9.I-synthesis iyinkimbinkimbi uma amapheya amabili noma ngaphezulu amabhondi e-disulfide edinga ukwakhiwa.Nakuba ukwakheka kwebhondi ye-disulfide kuvame ukuqedwa sekwephuzile esikimini sokwenziwa, ngezinye izikhathi ukwethulwa kwama-disulfides avele esenziwe ngaphambili kunenzuzo ekuxhumaniseni noma ekunwebeni amaketango e-peptide.I-Bzl iyiqembu elivikela i-Cys, i-Meb, i-Mob, i-tBu, i-Trt, i-Tmob, i-TMTr, i-Acm, i-Npys, njll., esetshenziswa kabanzi ku-symbiont.Sisebenza ngokukhethekile ku-disulphide peptide synthesis kuhlanganise:
1. Amapheya amabili we-disulfide bond akhiwa ngaphakathi kwe-molecule futhi amapheya amabili e-disulfide bond akhiwa phakathi kwama-molecule.
2. Amapheya amathathu ezibopho ze-disulfide akhiwa ngaphakathi kwe-molecule futhi amapheya amathathu e-disulfide bond akhiwa phakathi kwama-molecule.
3. Ukuhlanganiswa kwe-insulin polypeptide, lapho amapheya amabili esibopho se-disulfide akheka phakathi kokulandelana kwe-peptide okuhlukile
4. Ukuhlanganiswa kwamapheya amathathu e-disulfide-bonded peptides
Kungani i-cysteineyl amino group (Cys) ikhetheke kangaka?
I-side chain ye-Cys ineqembu elisebenza kakhulu elisebenzayo.Ama-athomu e-hydrogen kuleli qembu athathelwa indawo kalula ama-radicals mahhala namanye amaqembu, futhi ngaleyo ndlela angakha kalula izibopho ezihlangene namanye ama-molecule.
Izibopho ze-disulfide ziyingxenye ebalulekile yesakhiwo se-3D samaprotheni amaningi.Amabhondi ebhuloho e-disulphide anganciphisa ukunwebeka kwe-peptide, akhulise ukuqina, futhi anciphise inani lezithombe ezingaba khona.Lo mkhawulo wesithombe ubalulekile emsebenzini webhayoloji nokuzinza kwesakhiwo.Ukushintshwa kwayo kungase kube okumangalisayo ngesakhiwo sonke seprotheni.Ama-amino acid e-Hydrophobic afana namazolo, i-Ile, i-Val ayi-helix stabilizer.Ngoba iqinisa i-disulfide-bond α-helix yokwakheka kwe-cysteine noma ngabe i-cysteine ingenzi izibopho ze-disulfide.Okungukuthi, uma zonke izinsalela ze-cysteine bezisesimweni esincishisiwe, (-SH, ethwele amaqembu amahhala e-sulfhydryl), amaphesenti aphezulu wezingcezu ze-helical ayengenzeka.
Izibopho ze-disulfide ezakhiwe yi-cysteine zihlala isikhathi eside ekuzinzeni kwesakhiwo semfundo ephakeme.Ezimweni eziningi, amabhuloho e-SS phakathi kwamabhondi ayadingeka ukuze kwakhiwe izakhiwo ze-quaternary.Ngezinye izikhathi izinsalela ze-cysteine ezakha izibopho ze-disulfide ziqhelelene kakhulu nesakhiwo esiyinhloko.I-topology yamabhondi e-disulfide iyisisekelo sokuhlaziywa kwe-protein primary structure homology.Izinsalela ze-cysteine zamaprotheni angama-homologous zigcinwe kakhulu.I-tryptophan kuphela eyongiwe ngokwezibalo kune-cysteine.
I-cysteine itholakala phakathi nendawo ye-catalytic site ye-thiolase.I-Cysteine ingenza i-acyl intermediates ngqo ne-substrate.Ifomu elincishisiwe lisebenza "njengesigcina sesibabule" esigcina i-cysteine kumaprotheni esimweni esincishisiwe.Uma i-pH iphansi, ukulingana kuthanda ifomu le-SH elincishisiwe, kanti ezindaweni ezine-alkaline -SH ijwayele ukuba ne-oxidized ukuze yakhe -SR, kanti u-R uyinoma yini ngaphandle kwe-athomu ye-hydrogen.
I-Cysteine ingase futhi isabele nge-hydrogen peroxide kanye ne-organic peroxides njenge-detoxicant.
Isikhathi sokuthumela: May-19-2023