Phezulu, ukubunjwa kweebhondi ze-peptide, ukuvelisa i-dipeptides, yinkqubo yekhemikhali elula.Oku kuthetha ukuba amacandelo amabini e-amino acid adityaniswe yi-peptide bond, i-amide bond, ngelixa i-dehydrated.
Ukwenziwa kwe-peptide bond kukusebenza kwe-amino acid phantsi kweemeko zokusabela kancinci.(A) i-carboxyl moiety, i-amino acid yesibini (B) I-nucleophilic activated carboxyl moiety emva koko yenza idipeptide (AB)."Ukuba icandelo le-carboxyl (A) alikhuselwanga, ukubunjwa kwebhondi ye-peptide ayinakulawulwa."Iimveliso zombane ezifana ne-linear kunye ne-cyclic peptides zinokuxutywa kunye neekhompawundi ekujoliswe kuzo AB.Ke ngoko, onke amaqela asebenzayo angabandakanyekanga ekwenziweni kwebhondi ye-peptide kufuneka akhuselwe ngendlela enokubuyiselwa okwethutyana ngexesha le-peptide synthesis.
Ke, i-peptide synthesis-ukwenziwa kwebhondi nganye yepeptide-ibandakanya amanyathelo amathathu okudibanisa.
Inyathelo lokuqala kukulungisa ezinye ii-amino acids ezifuna ukukhuselwa, kwaye i-zwitterionic structure ye-amino acids ayisekho.
Inyathelo lesibini kukusabela kwamanyathelo amabini ukwenza iibhondi ze-peptide, apho iqela le-carboxyl le-N-ekhuselweyo ye-amino acid iqala isebenze kwi-intermediate esebenzayo kwaye emva koko i-peptide bond yenziwe.Le mpendulo idityanisiweyo ingenzeka njengenyathelo elinye okanye njengeempendulo ezimbini ezilandelelanayo.
Isinyathelo sesithathu kukususwa okukhethiweyo okanye ukususwa ngokupheleleyo kwesiseko sokukhusela.Nangona konke ukususwa kunokwenzeka kuphela emva kokuba onke amatyathanga e-peptide ehlanganiswe, ukususwa okukhethiweyo kwamaqela akhuselayo kuyafuneka ukuze kuqhutyekwe ne-peptide synthesis.
Ngenxa yokuba i-amino acids ezili-10 (i-Ser, i-Thr, iTyr, i-Asp, i-Glu, i-Lys, i-Arg, i-His, i-Sec kunye ne-Cys) iqulethe amaqela asebenzayo e-chain chain, efuna ukukhuselwa okukhethiweyo, okwenza i-peptide synthesis ibe nzima ngakumbi.Iziseko zokhuselo zethutyana kunye nesiqingatha-ezisisigxina kufuneka zihlulwe ngenxa yeemfuno ezahlukeneyo zokukhetha.Amaqela okukhusela okwethutyana asetyenziswa kwisinyathelo esilandelayo ukubonisa ukukhuselwa kwexeshana kwe-amino acid okanye amaqela asebenzayo e-carboxyl.Amaqela akhuselayo ahlala esisigxina ayasuswa ngaphandle kokuphazamisana neebhondi zepeptide esele zenziwe okanye amatyathanga e-amino acid ecaleni, ngamanye amaxesha ngexesha lokudibanisa.
"Ngokunqwenelekayo, ukusebenza kwecandelo le-carboxyl kunye nokwakheka okulandelayo kweebhondi ze-peptide (iimpendulo zokudibanisa) kufuneka zikhawuleze, ngaphandle kobuhlanga okanye ukwakheka kwemveliso, kwaye i-reactants ye-molar kufuneka isetyenziswe ukufezekisa isivuno esikhulu."Ngelishwa, akukho nanye yeendlela zokudibanisa imichiza eyanelisayo ezi mfuno, kwaye zimbalwa ezifanelekileyo ukudibanisa okusebenzayo.
Ngexesha le-peptide synthesis, amaqela asebenzayo abandakanyekayo kwiimpendulo ezahlukeneyo ngokuqhelekileyo adibaniswa neziko le-manual, i-glycine iyodwa kuphela, kwaye kukho umngcipheko wokujikeleza.
Isinyathelo sokugqibela kumjikelezo we-peptide synthesis kukususwa kwawo onke amaqela akhuselayo.Ukususwa okukhethiweyo kwamaqela okukhusela kubalulekile kwi-peptide chain extensions ngaphezu kwemfuneko yokususa ngokupheleleyo ukhuseleko kwi-dipeptide synthesis.Iindlela zokwenziwa kwezinto kufuneka zicwangciswe ngononophelo.Ngokuxhomekeke kukhetho olucwangcisiweyo, i-N inokukhetha ngokukhetha i-α-amino okanye amaqela okukhusela i-carboxyl.Igama elithi "iqhinga" libhekiselele kulandelelwano lwee-condensation reactions of individuals amino acids.Ngokubanzi, kukho umahluko phakathi kokudityaniswa kancinci kancinci kunye nokuxinana kwamaqhekeza.I-Peptide synthesis (ekwabizwa ngokuba yi "conventional synthesis") yenzeka kwisisombululo.Kwiimeko ezininzi, ukolula kancinci kancinci kwetsheyini yepeptide kunokwenziwa kuphela ngokusebenzisa ikhonkco lepeptide ukudibanisa amaqhekeza amafutshane.Ukudibanisa iipeptide ezinde, iimolekyuli ekujoliswe kuzo kufuneka zihlulwe zibe ngamaqhekeza afanelekileyo kwaye zizimisele ukuba zinokunciphisa inqanaba lokwahlula kwi-C terminus.Emva kokuba amaqhekeza ngamanye adityaniswe ngokuthe ngcembe, ikhompawundi ekujoliswe kuyo iya kudityaniswa.Isicwangciso se-peptide synthesis sibandakanya ukukhethwa kweyona nxalenye ilungileyo kunye neyona ifanelekileyo yokukhusela, kwaye isicwangciso se-peptide synthesis sibandakanya ukukhethwa kweyona ndlela ifanelekileyo yokudibanisa iziseko zokukhusela kunye neyona ndlela ilungileyo yokudibanisa iqhekeza.
Ixesha lokuposa: Jul-19-2023