Lub hom qauv ntawm cov protein

Protein qauv tej zaum yuav sawv cev los ntawm ib qhov ntawm plaub xaiv. Txhua xaiv nws muaj nws tus kheej peculiarities. Yog li, muaj tshwm sim ib tug quaternary, ternary, theem nrab thiab thawj qauv ntawm cov protein.

Qhov kawg theem nyob rau hauv daim ntawv no sawv cev rau ib tug linear polypeptide saw ntawm cov amino acids. Amino acids koom ua ke los ntawm peptide bonds. Lub hom qauv ntawm ib tug protein yog qhov nyuaj theem ntawm lub koom haum ntawm lub lwg me me. Los ntawm covalent peptide bonds ntawm cov alpha-amino pab pawg neeg ntawm ib tug amino acid thiab cov alpha-carboxyl pab pawg neeg ntawm lwm molecule muab siab stability.

Nyob rau hauv lub tsim ntawm peptide bonds nyob rau hauv lub hlwb yog tshuab txais thawj carboxyl pab pawg neeg. Tom qab kev twb kev txuas yog nrog ib tug amino pab pawg neeg. Kwv yees li tib yam kuaj ua polypeptide synthesis.

Peptide daim ntawv cog lus, uas yog ib tug rov chav tsev ntawm lub polypeptide saw muaj ib tug xov tooj ntawm cov nta. Nyob rau hauv tus ntawm cov nta tsis tau tsuas yog rau thawj qauv ntawm cov protein. Lawv muaj kev cuam tshuam ob leeg lub siab dua quas theem ntawm lub polypeptide saw. Ntawm cov ntsiab qhov txawv nta cais coplanarity (muaj peev xwm ntawm tag nrho cov atoms uas muaj nyob rau hauv lub peptide pab pawg neeg nyob rau hauv tib lub dav hlau) nrog rau kev hwm mus substituents trans-N-C linkages, cov cuab yeej muaj nyob rau hauv 2 resonance cov ntaub ntawv. Qhov tshwj xeeb nta ntawm lub peptide daim ntawv cog lus kuj muaj peev xwm mus tsim hydrogen bonds. Wherein txhua peptide ntawm cov pab pawg neeg tej zaum yuav tsim los ntawm ob tug hydrogen bonds nrog lwm pab pawg (xws li peptide). Txawm li cas los, muaj kev zam. Cov no muaj xws peptide pawg nrog rau cov amino pawg ntawm hydroxyproline los yog proline. Lawv muaj peev xwm tsim tsuas yog ib hydrogen daim ntawv cog lus. Qhov no muaj feem xyuam rau cov tsim ntawm protein theem nrab qauv. Yog li, lub feem twg yog hydroxyproline los yog proline, lub peptide saw yog yooj yim bent vim lub fact tias muaj yog ib tug thib ob hydrogen daim ntawv cog lus uas yuav kom nws (raws li feem ntau).

Lub npe yog tsim los ntawm cov amino acid peptide npe muaj nyob rau hauv lawv. Dipeptide muab ob amino acid tripeptide - peb, tetrapeptide - plaub, thiab li ntawm. Txhua polypeptide saw (los yog peptide) ntawm tej ntev yog tam sim no N-davhlau ya nyob twg amino acid, uas muaj ib tug dawb amino pab pawg neeg thiab cov C-davhlau ya nyob twg amino acid, nyob rau hauv uas muaj yog ib tug dawb carboxyl pab pawg neeg.

Thaj chaw ntawm proteins.

Nyob rau hauv txoj kev tshawb no ntawm cov tebchaw, zaum xav nyob rau hauv ob peb lub teeb meem. Cov soj ntsuam ntawm feem ntau nrhiav mus nrhiav tawm qhov luaj li cas, txiav txim seb tus duab thiab luj ntawm protein molecules. Nws yuav tsum tau muab sau tseg hais tias nws yog ib tug heev kev sib tw. Cov teeb meem no yog hais tias qhov kev txiav txim ntawm tus kwv tij molecular yuag mus nce lub ib kub npau npau kub ntawm cov protein ntau cov tshuaj (raws li yog ua li cas nyob rau hauv lwm yam) yog tsis yooj yim sua, vim lub fact tias cov protein cov ntsiab tsis rhaub. Ib tug txhais ntawm qhov ntsuas nyob rau hauv raws li txos ntawm lub khov kub yog tsis muaj tseeb. Nyob rau hauv tas li ntawd, cov proteins nyob rau hauv lub purest daim ntawv puas tau pom. Txawm li cas los, nrog kev pab los ntawm lub tsim txoj kev, nws twb pom hais tias cov molecular yuag yog hom twg los ntawm 14 mus rau 45 txhiab thiab ntau dua.

Ib qho tseem ceeb cov yam ntxwv ntawm lub tebchaw yog lub fractional salting tawm. Qhov no tus txheej txheem yog lub rho tawm ntawm proteins uas los ntawm cov tshuaj tom qab qhov sib ntxiv ntawm ntsev dlaws nrog sib txawv ntau.

Ib qho tseem ceeb cov yam ntxwv yog cov denaturation. Qhov no txoj kev yuav siv sij hawm qhov chaw nyob rau hauv lub nag lossis daus ntawm cov nqaijrog nrog hnyav hlau. Denaturation yog tsis tau kev ntuj zog. Qhov no txoj kev yuav cov conversion of txawv molecules, nyob rau hauv tas li ntawd mus rhuav lub polypeptide saw. Nyob rau hauv lwm yam lus, cov thawj qauv ntawm protein tseem unchanged thaum lub sij hawm denaturation.