Proteins (polypeptides, proteins) yog cov tshuaj macromolecular, uas suav nrog alpha-amino acids txuas nrog peptide daim ntawv cog lus. Cov muaj pes tsawg leeg ntawm cov proteins nyob rau hauv cov kab mob nyob yog txiav txim los ntawm cov noob caj noob ces code. Raws li txoj cai, cov synthesis siv cov txheej txheem ntawm 20 tus qauv amino acids.
YProtein classification
Kev sib cais ntawm cov protein yog ua raws li cov txheej txheem sib txawv:
- Cov duab ntawm lub molecule.
- Composition.
- Functions.
Raws li cov txheej txheem kawg, cov proteins raug cais tawm:
- Ntawm kev teeb tsa.
- Transport.
- Cov neeg cog lus.
Y
Structural proteins
Cov no suav nrog elastin, collagen, keratin, fibroin. Cov qauv polypeptides koom nrog hauv kev tsim cov cell membranes. Lawv tuaj yeem tsim cov channel lossis ua lwm yam haujlwm hauv lawv.
Nyob zoo, khaws cia proteins
Cov khoom noj khoom haus polypeptide yog casein. Vim nws, cov kab mob loj hlob yog muab nrog calcium, phosphorus thiabCov amino acids.
Reserve proteins yog cov noob cog qoob loo, qe dawb. Lawv tau noj thaum lub sij hawm kev loj hlob ntawm embryos. Nyob rau hauv tib neeg lub cev, xws li nyob rau hauv cov tsiaj, proteins tsis khaws cia nyob rau hauv cia. Lawv yuav tsum tsis tu ncua nrog zaub mov, txwv tsis pub txoj kev loj hlob ntawm dystrophy yuav zoo li.
thauj polypeptides
Hemoglobin yog ib qho piv txwv classic ntawm cov proteins. Lwm cov polypeptides koom nrog hauv kev txav ntawm cov tshuaj hormones, lipids thiab lwm yam tshuaj muaj nyob hauv cov ntshav.
Cell daim nyias nyias muaj cov proteins uas muaj peev xwm thauj cov ions, amino acids, qabzib thiab lwm cov khoom sib txuas thoob plaws cell membrane.
Y
Contractile proteins
Cov haujlwm ntawm cov polypeptides no cuam tshuam nrog kev ua haujlwm ntawm cov leeg nqaij. Tsis tas li ntawd, lawv muab kev txav ntawm cilia thiab flagella hauv protozoa. Contractile proteins ua lub luag haujlwm ntawm kev thauj cov organelles hauv lub cell. Vim lawv lub xub ntiag, kev hloov pauv hauv cov ntaub ntawv cellular tau ua kom ntseeg tau.
Piv txwv ntawm cov proteins uas muaj cov kab mob sib kis yog myosin thiab actin. Nws yog tsim nyog hais tias cov polypeptides pom tsis tau tsuas yog nyob rau hauv lub hlwb ntawm cov nqaij fibers. Contractile proteins ua lawv txoj hauj lwm nyob rau hauv yuav luag tag nrho cov tsiaj cov ntaub so ntswg.
Ntse
Ib tus neeg polypeptide, tropomyosin, muaj nyob hauv cov hlwb. Lub contractile nqaij protein myosin yog nws cov polymer. Nws tsim ib qho nyuaj nrog actin.
Cov nqaij leeg nqaij protein tsis yaj hauv dej.
Tus nqi ntawm polypeptide synthesis
Nws yog tswj hwm los ntawm cov thyroid thiabsteroid cov tshuaj hormones. Nkag mus rau hauv lub cell, lawv khi rau cov receptors tshwj xeeb. Cov tsim complex nkag mus rau hauv lub cell nucleus thiab khi rau chromatin. Qhov no nce tus nqi ntawm polypeptide synthesis ntawm qib noob.
Cov noob nquag muab kev sib txuas ntxiv ntawm qee yam RNA. Nws tawm hauv lub nucleus, mus rau lub ribosomes thiab activates lub synthesis ntawm tshiab structural los yog contractile proteins, enzymes los yog cov tshuaj hormones. Qhov no yog cov nyhuv anabolic ntawm cov noob.
Meanwhile, protein synthesis nyob rau hauv hlwb yog ib tug qeeb qeeb txheej txheem. Nws xav tau cov nqi zog siab thiab cov khoom siv yas. Yog li, cov tshuaj hormones tsis tuaj yeem tswj cov metabolism sai. Lawv txoj haujlwm tseem ceeb yog tswj kev loj hlob, sib txawv thiab kev loj hlob ntawm cov hlwb hauv lub cev.
Muscle contraction
Nws yog ib qho piv txwv tseem ceeb ntawm kev ua haujlwm ntawm cov proteins. Nyob rau hauv cov chav kawm ntawm kev tshawb fawb, nws tau pom tias lub hauv paus ntawm cov leeg nqaij contraction yog ib qho kev hloov nyob rau hauv lub cev lub cev ntawm cov polypeptide.
Lub luag haujlwm ua haujlwm yog ua los ntawm actomyosin protein, uas cuam tshuam nrog adenosine triphosphoric acid. Qhov kev sib txuas no yog nrog los ntawm kev cog lus ntawm myofibrils. Xws li kev sib cuam tshuam tuaj yeem pom sab nraum lub cev.
Piv txwv li, yog tias soaked hauv dej (macerated) cov nqaij fibers, tsis muaj excitability, raug rau ib tug tov ntawm adenosine triphosphate, lawv ntse contraction yuav pib, zoo ib yam li contraction ntawm cov leeg nqaij. Qhov kev paub no yog qhov tseem ceeb tshaj plaws ntawm kev siv. Nws ua pov thawj qhov tseeb tiasnqaij contraction yuav tsum muaj cov tshuaj tiv thaiv ntawm contractile proteins uas muaj zog-nplua nuj tshuaj.
Kev ua ntawm vitamin E
Ntawm qhov tod tes, nws yog lub ntsiab lus tseem ceeb hauv cov tshuaj tiv thaiv kab mob. Vitamin E tiv thaiv cov rog thiab lwm yam yooj yim oxidized tebchaw los ntawm oxidation. Nyob rau tib lub sijhawm, nws ua raws li cov khoom siv hluav taws xob thiab koom nrog cov tshuaj tiv thaiv redox, uas cuam tshuam nrog kev cia ntawm lub zog tso tawm.
vitamin E deficiency ua rau atrophy ntawm cov leeg nqaij: cov ntsiab lus ntawm contractile protein myosin yog sharply txo, thiab nws yog hloov los ntawm collagen, ib tug inert polypeptide.
Qhov tshwj xeeb ntawm myosin
Nws suav hais tias yog ib qho ntawm cov protein ua haujlwm tseem ceeb. Nws suav txog li 55% ntawm tag nrho cov ntsiab lus ntawm polypeptides hauv cov leeg nqaij.
Filaments (thick filaments) ntawm myofibrils yog ua los ntawm myosin. Lub molecule muaj ib tug ntev fibrillar ib feem, uas muaj ib tug ob-helix qauv, thiab lub taub hau (globular qauv). Myosin muaj 6 subunits: 2 hnyav thiab 4 lub teeb chains nyob rau hauv lub globular ib feem.
Lub luag haujlwm tseem ceeb ntawm thaj av fibrillar yog lub peev xwm los tsim cov pob ntawm myosin filaments lossis tuab protofibrils.
Ntawm lub taub hau yog qhov chaw nquag ntawm ATPase thiab qhov chaw ua haujlwm-binding. Qhov no ua kom ATP hydrolysis thiab khi rau actin filaments.
Ntau yam
Subtypes ntawm actin thiab myosin yog:
- Dynein ntawm flagella thiab ciliaprotozoa.
- Spectrin hauv erythrocyte daim nyias nyias.
Neurostenin ntawm perisynaptic membranes.
Cov kab mob polypeptides lub luag haujlwm rau kev txav ntawm ntau yam khoom hauv qhov concentration gradient tuaj yeem raug ntaus nqi rau ntau yam ntawm actin thiab myosin. Cov txheej txheem no tseem hu ua chemotaxis.
Lub luag haujlwm ntawm adenosine triphosphoric acid
Yog tias koj muab actomyosin filaments hauv cov kua qaub, ntxiv cov poov tshuaj thiab magnesium ions, koj tuaj yeem pom tias lawv luv luv. Hauv qhov no, qhov kev tawg ntawm ATP raug pom. Qhov tshwm sim no qhia tau hais tias kev tawg ntawm adenosine triphosphoric acid muaj qee qhov kev sib raug zoo nrog kev hloov pauv ntawm lub cev nqaij daim tawv ntawm cov protein thiab, yog li ntawd, nrog kev ua haujlwm ntawm cov leeg. Qhov tshwm sim no tau pom thawj zaug los ntawm Szent-Gyorgyi thiab Engelhardt.
Kev sib txuas thiab kev tawg ntawm ATP yog qhov tseem ceeb hauv cov txheej txheem ntawm kev hloov tshuaj zog rau hauv lub zog siv tshuab. Thaum lub sij hawm tawg ntawm glycogen, nrog rau kev tsim cov lactic acid, xws li dephosphorylation ntawm adenosine triphosphoric thiab creatine phosphoric acids, kev koom tes ntawm oxygen tsis tas yuav tsum tau. Qhov no piav qhia txog lub peev xwm ntawm cov leeg nqaij uas nyob ib leeg los ua haujlwm raws li cov xwm txheej anaerobic.
Lactic acid thiab cov khoom tsim thaum lub sij hawm tawg ntawm adenosine triphosphoric thiab creatine phosphoric acids accumulates nyob rau hauv cov nqaij fibers uas nkees thaum ua hauj lwm nyob rau hauv ib tug anaerobic ib puag ncig. Yog li ntawd, lub reserves ntawm cov khoom yog tas mus li, thaum lub sij hawm lub splitting ntawm uas tsim nyog lub zog yog tso tawm. Yog hais tias cov leeg nkees yog muab tso rau hauv ib qho chaw uas muaj oxygen, nws yuavhaus nws. Qee cov lactic acid yuav pib oxidize. Yog li ntawd, dej thiab carbon dioxide raug tsim. Lub zog tso tawm yuav raug siv rau kev rov ua dua ntawm creatine phosphoric, adenosine triphosphoric acids thiab glycogen los ntawm cov khoom lwj. Vim li no, cov leeg yuav rov muaj peev xwm ua haujlwm.
pob txha pob txha
Cov khoom ntiag tug ntawm polypeptides tsuas yog piav qhia los ntawm qhov piv txwv ntawm lawv txoj haujlwm, piv txwv li lawv txoj kev koom tes rau cov haujlwm nyuaj. Ntawm ob peb cov qauv uas muaj kev sib raug zoo ntawm cov protein thiab lub cev ua haujlwm, cov leeg pob txha tsim nyog tshwj xeeb.
Nws lub xovtooj tau qhib los ntawm cov hlab ntsha impulses (membrane-directed signals). Molecularly, kev cog lus yog raws li kev caij tsheb kauj vab ntawm kev hla choj los ntawm kev sib cuam tshuam ntawm cov actin, myosin, thiab Mg-ATP. Calcium-binding proteins thiab Ca ions ua tus neeg nruab nrab ntawm cov nyhuv thiab cov paj hlwb.
Kev sib haum xeeb txwv qhov ceev ntawm cov lus teb rau "on / off" impulses thiab tiv thaiv kev sib cog lus. Nyob rau tib lub sijhawm, qee qhov oscillations (fluctuations) ntawm flywheel nqaij fibers ntawm tis kab yog tswj tsis tau los ntawm ions los yog zoo sib xws low-molecular compounds, tab sis ncaj qha los ntawm contractile proteins. Vim li no, kev cog lus sai heev tuaj yeem ua tau, uas, tom qab ua kom tiav, ua haujlwm ntawm lawv tus kheej.
Ua kua siv lead ua khoom ntawm polypeptides
Thaum ua kom cov leeg nqaij luvlub sij hawm ntawm lub lattice tsim los ntawm protofibrils hloov. Thaum lub lattice ntawm nyias filaments nkag mus rau hauv cov qauv ntawm cov ntsiab lus tuab, tetragonal symmetry yog hloov los ntawm hexagonal. Qhov tshwm sim no tuaj yeem suav hais tias yog kev hloov pauv ntawm polymorphic hauv cov kua siv lead ua kua.
Txhim kho cov txheej txheem mechanochemical
Lawv kub mus rau kev hloov pauv ntawm cov tshuaj muaj zog rau hauv lub zog siv tshuab. ATP-ase kev ua haujlwm ntawm mitochondrial cell membranes zoo ib yam li kev ua ntawm iosin system ntawm cov leeg pob txha. Cov yam ntxwv tseem ceeb kuj tau sau tseg hauv lawv cov khoom siv kho tshuab: lawv raug txo qis los ntawm ATP.
Yog li ntawd, ib qho kev cog lus protein yuav tsum muaj nyob rau hauv daim nyias nyias mitochondrial. Thiab nws yeej nyob ntawd. Nws tau raug tsim los hais tias kev cog lus polypeptides koom nrog hauv mitochondrial mechanochemistry. Txawm li cas los xij, nws kuj tau muab tawm tias phosphatidylinositol (membrane lipid) kuj ua lub luag haujlwm tseem ceeb hauv cov txheej txheem.
Extra
Lub myosin protein molecule tsis tsuas yog pab txhawb kev sib cog lus ntawm ntau cov leeg, tab sis kuj tuaj yeem koom nrog lwm cov txheej txheem intracellular. Qhov no, tshwj xeeb, yog hais txog kev txav ntawm organelles, txuas ntawm actin filaments rau daim nyias nyias, tsim thiab ua haujlwm ntawm cytoskeleton, thiab lwm yam. Yuav luag ib txwm, cov molecule cuam tshuam ib txoj hauv kev los yog lwm yam nrog actin, uas yog qhov tseem ceeb thib ob ntawm kev cog lus. protein ntau.
Nws tau raug pov thawj tias actomyosin molecules tuaj yeem hloov qhov ntev raws li kev cuam tshuam ntawm cov tshuaj lom neeg lub zog tso tawm thaum cov phosphoric acid residue yog cleaved los ntawm ATP. Hauv lwm lo lus, txheej txheem noua rau cov leeg nqaij contraction.
Lub ATP system yog li ua ib yam ntawm cov khoom siv hluav taws xob. Raws li xav tau, nws hloov ncaj qha mus rau hauv ib qho khoom siv los ntawm actomyosin. Nyob rau tib lub sijhawm, tsis muaj cov yam ntxwv ntawm theem nrab ntawm cov txheej txheem ntawm kev sib cuam tshuam ntawm lwm cov ntsiab lus - kev hloov mus rau thermal zog.
