Ntau cov organic tshuaj uas ua rau lub cell muaj sia nyob yog tus yam ntxwv ntawm qhov loj me me thiab yog biopolymers. Cov no suav nrog cov proteins, uas tsim los ntawm 50 mus rau 80% ntawm qhov qhuav ntawm tag nrho cov cell. Protein monomers yog cov amino acids uas txuas ua ke los ntawm peptide bonds. Protein macromolecules muaj ob peb theem ntawm lub koom haum thiab ua ib tug xov tooj ntawm lub luag hauj lwm tseem ceeb nyob rau hauv lub cell: lub tsev, tiv thaiv, catalytic, lub cev muaj zog, thiab lwm yam nyob rau hauv peb tsab xov xwm, peb yuav xav txog cov yam ntxwv ntawm peptides, thiab kuj muab piv txwv ntawm globular thiab fibrillar proteins. uas ua rau tib neeg lub cev.
Cov duab ntawm lub koom haum ntawm polypeptide macromolecules
Amino acid residue tau txuas mus rau ib leeg los ntawm cov nyiaj muaj zog covalent hu uapeptide. Lawv muaj zog heev thiab khaws cov qauv ntawm cov protein nyob rau hauv lub xeev ruaj khov, uas muaj cov qauv ntawm cov saw hlau. Daim ntawv thib ob tshwm sim thaum cov saw hlau polypeptide twisted rau hauv alpha helix. Nws yog stabilized los ntawm qhov tseem ceeb tshaj tawm hydrogen bonds. Lub tertiary, los yog haiv neeg, configuration yog qhov tseem ceeb, vim hais tias feem ntau ntawm cov globular proteins nyob rau hauv ib tug cell nyob tsuas muaj xws li ib tug qauv. Cov kauv yog ntim rau hauv daim ntawv ntawm ib tug kheej kheej los yog globule. Nws txoj kev ruaj ntseg yog vim tsis tsuas yog cov tsos ntawm cov tshiab hydrogen bonds, tab sis kuj mus rau tsim ntawm disulfide txuas hniav. Lawv tshwm sim los ntawm kev sib cuam tshuam ntawm sulfur atoms uas tsim cov amino acid cysteine . Lub luag haujlwm tseem ceeb hauv kev tsim cov qauv tertiary yog ua los ntawm hydrophilic thiab hydrophobic kev sib cuam tshuam ntawm pawg ntawm atoms hauv cov qauv peptide. Yog hais tias ib tug globular protein ua ke nrog tib lub molecules los ntawm ib tug uas tsis yog-protein tivthaiv, piv txwv li, ib tug hlau ion, ces ib tug quaternary configuration tshwm sim - lub siab tshaj plaws daim ntawv ntawm lub koom haum ntawm cov polypeptide.
YFibrillar proteins
Cov contractile, lub cev muaj zog thiab lub tsev ua haujlwm hauv lub cell yog ua los ntawm cov proteins, cov macromolecules uas zoo li nyias nyias - fibrils. Cov polypeptides uas tsim cov fibers ntawm daim tawv nqaij, plaub hau, thiab rau tes yog cais raws li hom fibrillar. Qhov nrov tshaj plaws ntawm lawv yog collagen, keratin thiab elastin. Lawv tsis yaj hauv dej, tab sis tuaj yeem o hauv nws, tsim cov nplaum nplaum thiab khov. Peptides ntawm cov qauv linear kuj yog ib feem ntawm fission spindle filaments, tsim cov mitotic apparatus ntawm tes. Lawv yogtxuas mus rau chromosomes, cog lus thiab ncab lawv mus rau cov ncej ntawm tes. Cov txheej txheem no tau pom nyob rau hauv anaphase ntawm mitosis - kev faib tawm ntawm somatic hlwb ntawm lub cev, nrog rau kev txo qis thiab sib npaug theem ntawm kev faib cov kab mob - meiosis. Tsis zoo li globular protein, fibrils muaj peev xwm ncab sai thiab cog lus. Lub cilia ntawm ciliates-khau, flagella ntawm euglena ntsuab lossis unicellular algae - chlamydomonas yog tsim los ntawm fibrils thiab ua haujlwm ntawm kev txav mus los hauv cov kab mob yooj yim tshaj plaws. Kev cog lus ntawm cov leeg nqaij - actin thiab myosin, uas yog ib feem ntawm cov leeg nqaij, txiav txim siab ntau yam kev txav ntawm cov leeg pob txha thiab tuav cov pob txha pob txha ntawm tib neeg lub cev.
qauv ntawm globular proteins
Peptides - nqa cov molecules ntawm ntau yam tshuaj, tiv thaiv cov proteins - immunoglobulins, cov tshuaj hormones - qhov no yog cov npe tsis tiav ntawm cov proteins, cov qauv tertiary uas muaj cov pob - globules. Muaj qee cov proteins hauv cov ntshav uas muaj qee qhov chaw ntawm lawv qhov chaw - cov chaw ua haujlwm. Nrog lawv cov kev pab, lawv paub thiab txuas mus rau lawv tus kheej cov molecules ntawm biologically active tshuaj uas ua los ntawm cov qog ntawm sib xyaw thiab sab hauv secretion. Nrog kev pab los ntawm globular proteins, cov tshuaj hormones ntawm cov thyroid thiab cov qog nqaij hlav, qog adrenal, thymus, pituitary caj pas raug xa mus rau qee lub hlwb ntawm tib neeg lub cev, nruab nrog cov receptors tshwj xeeb rau lawv qhov kev lees paub.
Membrane polypeptides
Cov kua dej-mosaic qauv ntawm cov qauv ntawm cov cell membranes yog qhov zoo tshaj plaws rau lawv cov haujlwm tseem ceeb: kev thaiv,receptor thiab thauj. Cov proteins uas muaj nyob rau hauv nws nqa tawm kev thauj mus los ntawm ions thiab hais txog tej yam khoom, xws li qabzib, amino acids, thiab lwm yam. Cov khoom ntawm globular carrier proteins yuav kawm tau siv lub sodium-potassium twj tso kua mis ua piv txwv. Nws nqa tawm kev hloov ntawm ions los ntawm lub cell mus rau qhov chaw intercellular thiab vice versa. Sodium ions tas li txav mus rau hauv nruab nrab ntawm lub cell cytoplasm, thiab cov poov tshuaj cations tas li tsiv tawm ntawm lub cell. Kev ua txhaum ntawm qhov xav tau concentration ntawm cov ions no ua rau kev tuag ntawm tes. Txhawm rau tiv thaiv qhov kev hem thawj no, cov protein tshwj xeeb yog tsim rau hauv cov cell membrane. Cov qauv ntawm globular proteins yog xws li hais tias lawv nqa cov cations Na+ thiab K+tawm tsam qhov concentration gradient siv lub zog ntawm adenosine triphosphoric acid.
qauv thiab kev ua haujlwm ntawm insulin
Soluble proteins ntawm kheej kheej qauv, uas yog nyob rau hauv tertiary daim ntawv, ua raws li regulators ntawm metabolism hauv tib neeg lub cev. Insulin yog tsim los ntawm beta hlwb ntawm islets ntawm Langerhans thiab tswj cov ntshav qabzib. Nws muaj ob lub polypeptide chains (α- thiab β-forms) txuas los ntawm ob peb tus choj disulfide. Cov no yog covalent bonds uas tshwm sim ntawm cov molecules ntawm sulfur-muaj amino acid - cysteine . Cov tshuaj hormones pancreatic feem ntau muaj cov kab ke ntawm cov amino acid units tau tsim nyob rau hauv daim ntawv ntawm alpha helix. Ib feem me me ntawm nws muaj daim ntawv ntawm β-structure thiab amino acid residues yam tsis muaj kev taw qhia nruj hauv qhov chaw.
Hmoglobin
Ib qho piv txwv classic ntawm globular peptidesCov protein hauv cov ntshav uas ua rau cov ntshav liab yog hemoglobin. Cov protein muaj plaub cheeb tsam polypeptide nyob rau hauv daim ntawv ntawm alpha thiab beta helices, uas yog kev cob cog rua los ntawm ib tug non-protein tivthaiv - heme. Nws yog sawv cev los ntawm ib tug hlau ion uas khi polypeptide chains rau hauv ib qho kev pom zoo muaj feem xyuam rau daim ntawv quaternary. Cov pa oxygen txuas mus rau cov protein molecule (nyob rau hauv daim ntawv no nws yog hu ua oxyhemoglobin) thiab ces thauj mus rau lub hlwb. Qhov no ua kom cov txheej txheem sib txawv ntawm cov txheej txheem sib txawv, txij li txhawm rau kom tau txais lub zog, lub cell oxidizes cov organic uas tau nkag mus rau nws.
Lub luag haujlwm ntawm cov ntshav protein hauv kev thauj roj
Ntxiv rau cov pa, hemoglobin tseem tuaj yeem txuas cov pa roj carbon dioxide. Cov pa roj carbon dioxide yog tsim los ntawm cov khoom ntawm catabolic cellular cov tshuaj tiv thaiv thiab yuav tsum tau muab tshem tawm ntawm lub hlwb. Yog tias cov pa nqus tau pa muaj cov pa roj carbon monoxide - carbon monoxide, nws tuaj yeem tsim kev sib raug zoo nrog hemoglobin. Nyob rau hauv cov ntaub ntawv no, ib tug tsis muaj kob thiab tsw ntxhiab tshuaj lom nyob rau hauv tus txheej txheem ntawm ua pa sai sai nkag mus rau hauv lub hlwb ntawm lub cev, ua rau lom. Tshwj xeeb yog rhiab heev rau siab concentration ntawm carbon monoxide yog cov qauv ntawm lub hlwb. Muaj qhov tuag tes tuag taw ntawm qhov chaw ua pa nyob hauv medulla oblongata, uas ua rau tuag los ntawm kev ua pa.
Nyob hauv peb tsab xov xwm, peb tau tshuaj xyuas cov qauv, qauv thiab cov khoom ntawm peptides, thiab kuj tau muab piv txwv ntawm globular proteins uas ua tau ntau yam tseem ceeb hauv tib neeg lub cev.
