Keratin yog hmoovib tug fibrous protein tsim los ntawm tsiaj epithelial hlwb. Cov khoom tseem ceeb uas ua rau cov plaub hau, plaub, horns, armor, hooves, txhob lo lo ntxhuav, thiab lwm yam, muaj kev tiv thaiv zoo rau cov tsiaj. Nws tuaj yeem muab faib ua ob pawg: ib qho yog alpha keratin, uas yog cov protein muaj nyob hauv cov plaub hau, horns, rau tes, hooves, thiab lwm yam., nrog cov ntsiab lus cysteine ntau hauv cov molecule; Lwm hom yog beta keratin, xws li silk fibroin, uas tsis muaj cysteine lossis cysteine hauv nws cov molecule, tab sis muaj qib siab glycine, alanine, thiab serine. Cov khoom siv tshuaj muaj zog heev, nrog rau cov ntsiab lus siab ntawm disulfide bonds. Raws li ib txwm muaj, nws yog insoluble hauv dej, ntsev tov, dilute acids, thiab dilute alkali daws, tab sis muaj peev xwm yaj nyob rau hauv inorganic sulfide daws. Kev lag luam tawv siv cov tshuaj inorganic sulfides tshem tawm cov tawv nqaij los ntawm kev siv cov cuab yeej no. Wool thiab silk, feem ntau yog tsim los ntawm keratin, yog cov ntaub ntawv tseem ceeb heev. Cov kab mob fibroin yog keratin, uas suav rau 70-75% ntawm cov lo lo ntxhuav thiab yog ib feem ntawm cov txhob lo lo ntxhuav. Nws txheej txheej yog coated nrog sericin (ib hom globulin), uas suav txog li 22-24%. Nws tsis yog filamentous thiab tuaj yeem yaj hauv dej kub. Hauv kev lag luam txhob lo lo ntxhuav, cov txhob lo lo ntxhuav ntuj (feem ntau hu ua cov lo lo ntxhuav nyoos) yuav tsum tau muab rhaub hauv dej kom yaj thiab tshem tawm sericin protein, thiaj li yuav ua kom cov txhob lo lo ntxhuav ntuj rau hauv ci thiab mos mos fibers rau weaving.
1. Mechanical method
Cov tshuab rho tawm ntawm keratin feem ntau suav nrog cua sov thiab siab kom tawg thiab hydrolyze disulfide bonds ntawm thiab txawm nyob rau hauv keratin molecules nyob rau hauv cov plaub hau fibers, yog li tig keratin nyob rau hauv cov plaub hau rau soluble keratin. Cov txheej txheem siv tshuab tuaj yeem muab faib ua cov txheej txheem high-pressure hydrolysis thiab high-pressure expansion method, extrusion method thiab extrusion method. Thaum lub sij hawm hydrolysis txheej txheem, kua qaub thiab alkali yuav muab ntxiv rau cov tshuaj tiv thaiv kettle los tsim high-temperature pressurized dilute acid hydrolysis txoj kev thiab high-temperature pressurized dilute alkali hydrolysis txoj kev, feem. Ntawm lawv, txoj kev nthuav dav yog qhov zoo dua vim tias nws qhov kub ntawm hydrolysis yog qhov qis, lub sijhawm luv luv, thiab cov khoom yog xoob thiab yooj yim rau hmoov.
2. Cov txheej txheem tshuaj
Raws li cov ntaub ntawv sib txawv thiab cov tshuaj reagents siv, cov txheej txheem tshuaj feem ntau tuaj yeem muab faib ua cov tshuaj acid-puag, txo qis, oxidation, thiab lwm yam. Thaum dissolving keratin los ntawm cov txheej txheem tshuaj, qee qhov nyiaj ntawm cov tshuaj denaturing, surfactants, thiab lwm yam. cuam tshuam cov rog intermolecular, hydrogen bonds, thiab lwm yam, txhawm rau ua kom cov solubility ntawm keratin molecules.
Cov txheej txheem tseem ceeb ntawm kev kho cov kua qaub-puag yog thawj zaug o ntawm cov plaub hau nrog cov kua qaub los yog alkali, thiab tom qab ntawd hydrolyze nws ntawm qhov kub thiab txias kom tau cov keratin soluble. Txhawm rau txhim kho kev ua kom tawg, feem ntau nws yog qhov yuav tsum tau siv nws ua ke nrog tus neeg sawv cev txo qis. Thaum lub sijhawm txheej txheem no, qhov concentration ntawm acidity thiab alkalinity, nrog rau qhov kub thiab txias ntawm cov tshuaj tiv thaiv, tuaj yeem cuam tshuam qhov hnyav molecular thiab tawm los ntawm keratin. Thaum lub sij hawm acid-base dissolution txheej txheem, muaj inevitably hydrolysis ntawm peptide bonds thiab decomposition ntawm disulfide bonds nyob rau hauv protein macromolecules. Yog li ntawd, nyob rau hauv txoj kev no, qhov tsis sib haum xeeb ntawm kev tawm los thiab molecular hnyav ntawm keratin yuav tsum tau daws. Feem ntau, keratin nrog qhov hnyav dua molecular tuaj yeem tau txais hauv lub sijhawm luv luv, tab sis cov txiaj ntsig ntawm keratin qis dua; Txawm li cas los xij, kev sib cais ntev ntev tuaj yeem yooj yim ua rau peptide daim ntawv cog lus hauv keratin molecules tawg, ua rau cov khoom hnyav dua molecular; Qhov siab dua qhov tawm los ntawm cov khoom soluble keratin, qhov me me nws qhov hnyav molecular.
2.2 Txoj kev txo qis siv tus neeg sawv cev txo qis los txo cov nyiaj disulfide hauv keratin molecules rau thiol pawg, ua rau cov keratin soluble. Cov tshuaj txo qis siv feem ntau yog cov tshuaj thiol, xws li sodium mercaptoacetate, 2-mercaptoethanol, mercaptoacetic acid, thiab dithiothreitol. Cov keratin uas muaj ntau ntawm thiol pawg tau txais los ntawm kev txo qis yuav tsum tau tiv thaiv nrog cov reagents tsim nyog vim muaj qhov muaj zog ntawm thiol pawg, uas yooj yim oxidized, thiaj li yuav tau txais cov tshuaj keratin ruaj khov; Feem ntau, surfactants xws li sodium dodecyl sulfonate [22] los yog rhamnolipids yog siv los tiv thaiv thiol pawg. Cov tshuaj no tseem tuaj yeem txo qhov nro ntawm keratin molecules thiab ua kom cov solubility ntawm keratin [23]. Tsis tas li ntawd, hlau sulfides kuj tseem siv tau los ua cov tshuaj txo qis, xws li sodium sulfide, uas tuaj yeem txo cov disulfide bonds thiab yaj keratin; Guanidine los yog guanidine hydrochloride tuaj yeem siv los ua kom tag nrho cov saw peptide, nthuav tawm cov pab pawg ua haujlwm tiav, thiab tom qab ntawd txo thiab rho tawm nrog tus neeg sawv cev denaturing. Siv kev sib xyaw ua ke ntawm cov tshuaj txo qis: sulfite / carboxamide tebchaw / sodium ntsev cov organic sib xyaw ua ke nrog cov khoom siv raw, siv kev txo qis kom qhib cov ntawv cog lus disulfide, thiab tom qab ntawd tiv thaiv keratin nrog surfactants tuaj yeem tiv thaiv keratin oxidation. Qhov hnyav molecular faib ntawm cov khoom tseem ceeb yog nyob nruab nrab ntawm 40-80kD. Cov reagents siv nyob rau hauv txoj kev txo qis kuj yog me me, tsis tshua muaj kev puas tsuaj rau cov peptide saw, uas ua rau ntau dua molecular hnyav thiab tawm los ntawm cov khoom keratin; Feem ntau txoj kev nyiam tshuaj extraction.
3 Txoj kev oxidation
Lub hauv paus ntsiab lus tseem ceeb yog siv oxidants los oxidize cov disulfide bonds nyob rau hauv keratin rau hauv sulfonic acid pawg, ua soluble keratin.
Cov oxidants siv nyob rau hauv txoj kev oxidation feem ntau yog peroxides xws li formic acid, peracetic acid, thiab hydrogen peroxide. Sulfonation nrog Na2SO3 thiab oxidation nrog cupric ammonium hydroxide hloov cystine pab pawg neeg rau hauv S-thiocysteine, thiab centrifugate gel zoo li keratin nrog ib tug me me lub ntiajteb txawj nqus pub filtration system. Cais cov gel zoo li cov tshuaj S-sulfonated keratin derivative heev, ntxiv tus neeg sawv cev chelating, thiab tom qab ntawd siv cov txheej txheem isoelectric point los nag thiab cais cov protein nruab nrab thiab S-sulfonated keratin siab sulfur protein. Txawm li cas los xij, thaum lub sij hawm oxidation txheej txheem, qhov tshwm sim ntawm peptide saw oxidative puas yuav inevitably tshwm sim, yog li qhov nruab nrab molecular hnyav ntawm keratin tau los ntawm txoj kev oxidation tsis siab.
4 Txoj Cai Lij Choj
Txoj hauv kev tseem ceeb yog siv cov degradation ntawm keratin los ntawm keratinase kom zom cov keratin insoluble rau hauv cov keratin soluble. Vim yog qhov tshwj xeeb degradation muaj nuj nqi ntawm ntuj keratin los ntawm keratinase, nws tuaj yeem txhim kho cov solubility ntawm keratin. Txawm li cas los xij, txoj kev no feem ntau siv sijhawm ntev thiab cov khoom siv feem ntau yog peptides nrog qis dua molecular hnyav.
Yolanda
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