Cov protein yog cov roj ntsha polymers nrog cov qauv tsim. Lawv muaj qhov hnyav molecular thiab muaj cov amino acids, cov pab pawg prosthetic sawv cev los ntawm cov vitamins, lipid thiab carbohydrate suav nrog. Proteins uas muaj carbohydrates, vitamins, hlau los yog lipids yog hu ua complex. Cov proteins yooj yim tsuas yog muaj cov amino acids txuas los ntawm peptide bonds.
YPeptides
Txawm hais tias cov qauv dab tsi muaj, cov monomers ntawm cov proteins yog cov amino acids. Lawv tsim cov hauv paus polypeptide saw, los ntawm cov fibrillar los yog globular qauv ntawm cov protein yog ces tsim. Nyob rau tib lub sijhawm, cov protein tsuas tuaj yeem ua ke hauv cov ntaub so ntswg nyob - hauv cov nroj tsuag, kab mob, fungal, tsiaj txhu thiab lwm cov hlwb.
Cov kab mob tib yam uas tsis tuaj yeem sib txuas cov protein monomers yog cov kab mob thiab protozoa. Tag nrho lwm tus muaj peev xwm tsim cov txheej txheem protein. Tab sis cov tshuaj dab tsi yog protein monomers, thiab lawv tsim li cas? Nyeem txog qhov no thiab hais txog cov protein biosynthesis, txog polypeptides thiab tsim cov qauv protein complex, txog amino acids thiab lawv cov khoom.hauv qab no.
Tsuas yog monomer ntawm cov protein molecule yog ib qho alpha-amino acid. Ib qho protein yog polypeptide, ib txoj hlua ntawm cov amino acids txuas. Nyob ntawm seb muaj pes tsawg tus amino acids koom nrog nws tsim, dipeptides (2 residues), tripeptides (3), oligopeptides (muaj 2-10 amino acids) thiab polypeptides (ntau cov amino acids) raug cais tawm.
Protein qauv tshuaj xyuas
Cov qauv Protein tuaj yeem yog thawj, me ntsis nyuaj - theem nrab, ntau dua - tertiary, thiab qhov nyuaj tshaj plaws - quaternary.
Cov qauv tseem ceeb yog cov saw yooj yim rau hauv cov protein monomers (amino acids) txuas los ntawm peptide daim ntawv cog lus (CO-NH). Cov qauv thib ob yog alpha helix lossis beta folds. Tertiary yog ib qho nyuaj tshaj peb-dimensional protein qauv, uas yog tsim los ntawm cov theem nrab vim yog tsim ntawm covalent, ionic thiab hydrogen bonds, nrog rau hydrophobic kev sib tshuam.
Cov qauv quaternary yog qhov nyuaj tshaj plaws thiab yog tus yam ntxwv ntawm cov protein receptors nyob rau ntawm cov cell membranes. Qhov no yog ib qho supramolecular (domain) qauv tsim los ntawm kev sib xyaw ntawm ntau lub molecules nrog cov qauv tertiary, ntxiv nrog cov carbohydrates, lipid lossis vitamin pawg. Nyob rau hauv cov ntaub ntawv no, raws li nyob rau hauv cov ntaub ntawv ntawm thawj, theem nrab thiab tertiary qauv, cov monomers ntawm cov proteins yog alpha-amino acids. Lawv kuj txuas nrog peptide bonds. Qhov txawv tsuas yog qhov nyuaj ntawm cov qauv.
Amino acids
Tsuas yog monomersprotein molecules yog alpha amino acids. Tsuas muaj 20 leej xwb, thiab lawv yuav luag yog lub hauv paus ntawm lub neej. Ua tsaug rau qhov pom ntawm peptide daim ntawv cog lus, protein synthesis ua tau. Thiab cov protein nws tus kheej tom qab ntawd pib ua cov qauv tsim, receptor, enzymatic, thauj, mediator thiab lwm yam haujlwm. Ua tsaug rau qhov no, lub cev muaj sia ua haujlwm thiab muaj peev xwm rov tsim dua.
Alpha amino acid nws tus kheej yog cov organic carboxylic acid nrog cov amino pawg txuas nrog alpha carbon atom. Cov tom kawg yog nyob ib sab ntawm pawg carboxyl. Hauv qhov no, cov protein monomers raug suav hais tias yog cov khoom siv organic uas lub davhlau ya nyob twg carbon atom nqa ob qho tib si amine thiab carboxyl pawg.
Kev sib txuas ntawm cov amino acids hauv peptides thiab cov proteins
Amino acids txuas rau hauv dimers, trimers thiab polymers los ntawm peptide daim ntawv cog lus. Nws yog tsim los ntawm cleavage ntawm ib pawg hydroxyl (-OH) los ntawm carboxyl site ntawm ib alpha-amino acid thiab hydrogen (-H) los ntawm cov amino pawg ntawm lwm alpha-amino acid. Raws li qhov tshwm sim ntawm kev sib cuam tshuam, dej tau muab cais tawm, thiab qhov chaw C=O nrog ib qho hluav taws xob dawb nyob ze ntawm cov pa roj carbon ntawm cov carboxyl residue tseem nyob ntawm carboxyl kawg. Hauv cov amino pawg ntawm lwm cov kua qaub, muaj qhov seem (NH) nrog cov dawb radical uas twb muaj lawm ntawm nitrogen atom. Qhov no tso cai rau ob lub radicals sib txuas los tsim ib daim ntawv cog lus (CONH). Nws hu ua peptide.
Alpha amino acid variants
Muaj 23 paub alpha-amino acids. Lawv yogCov npe xws li: glycine, valine, alanine, isolecine, leucine, glutamate, aspartate, ornithine, threonine, serine, lysine, cystine, cysteine, phenylalanine, methionine, tyrosine, proline, tryptophan, hydroxyproline, arginine, asparagine, histgl. Nyob ntawm seb lawv puas tuaj yeem tsim los ntawm tib neeg lub cev, cov amino acids tau muab faib ua qhov tsis tseem ceeb thiab tsis tseem ceeb.
Lub tswvyim ntawm tsis tseem ceeb thiab qhov tseem ceeb amino acids
Hloov pauv tuaj yeem tsim los ntawm tib neeg lub cev, thaum cov khoom tseem ceeb tsuas yog los ntawm zaub mov xwb. Nyob rau tib lub sijhawm, ob qho tib si tseem ceeb thiab tsis tseem ceeb acids yog qhov tseem ceeb rau biosynthesis protein, vim tias tsis muaj lawv cov synthesis tsis tuaj yeem ua tiav. Yog tsis muaj ib qho amino acid, txawm tias tag nrho lwm tus nyob, nws tsis tuaj yeem tsim cov protein ntau uas lub cell xav tau los ua nws txoj haujlwm.
Ib qho yuam kev ntawm ib qho ntawm cov theem ntawm biosynthesis - thiab cov protein tsis tsim nyog lawm, vim tias nws yuav tsis tuaj yeem sib sau ua ke rau hauv cov qauv uas xav tau vim yog kev ua txhaum ntawm cov hluav taws xob ntom ntom thiab kev sib cuam tshuam. Yog li ntawd, nws yog ib qho tseem ceeb rau ib tug neeg (thiab lwm yam kab mob) noj cov zaub mov protein uas muaj cov amino acids tseem ceeb. Lawv tsis nyob hauv cov zaub mov ua rau muaj ntau cov protein metabolism tsis zoo.
txheej txheem ntawm kev tsim daim ntawv cog lus peptide
Tsuas yog monomers ntawm cov proteins yog alpha-amino acids. Lawv maj mam sib xyaw ua ke rau hauv cov saw hlau polypeptide, cov qauv uas tau muab khaws cia rau hauv cov caj ces ntawm DNA (lossis RNA, yog tias cov kab mob biosynthesis raug txiav txim siab). Ib qho protein yog qhov nruj ntawm cov amino acid residues. Qhov no yog ib tug saw txiav nyob rau hauv ib tug tej yamib tug qauv uas ua ib tug pre-programmed muaj nuj nqi nyob rau hauv ib tug cell.
qib theem ntawm cov protein biosynthesis
Cov txheej txheem ntawm kev tsim cov protein muaj cov saw ntawm cov kauj ruam: rov ua dua ntawm DNA (lossis RNA) ntu, kev sib txuas ntawm cov ntaub ntawv hom RNA, nws tso tawm rau hauv cytoplasm ntawm tes los ntawm lub hauv paus, kev sib txuas nrog ribosome thiab maj mam txuas ntawm cov amino acid residues uas tau muab los ntawm kev hloov RNA. Ib yam khoom uas yog cov protein monomer koom nrog cov tshuaj tiv thaiv enzymatic ntawm kev tshem tawm cov pab pawg hydroxyl thiab hydrogen proton, thiab tom qab ntawd koom nrog cov saw hlau loj hlob ntawm polypeptide.
Yog li, cov saw hlau polypeptide tau txais, uas, twb tau nyob hauv cellular endoplasmic reticulum, raug txiav txim rau hauv qee qhov kev txiav txim siab thiab ntxiv nrog cov carbohydrate lossis lipid residue, yog tias xav tau. Qhov no yog hu ua cov txheej txheem ntawm "maturing" cov protein, tom qab uas nws raug xa los ntawm kev thauj cellular system mus rau nws qhov chaw.
YFunctions of synthesized proteins
Protein monomers yog cov amino acids tsim nyog los tsim lawv cov qauv tseem ceeb. Cov qauv theem nrab, tertiary thiab quaternary yog twb tsim los ntawm nws tus kheej, txawm hais tias qee zaum nws kuj xav tau kev koom tes ntawm enzymes thiab lwm yam khoom. Txawm li cas los xij, lawv tsis yog qhov tseem ceeb ntxiv lawm, txawm hais tias lawv yog qhov tseem ceeb rau cov protein ua lawv txoj haujlwm.
Amino acid, uas yog protein monomer, tuaj yeem muaj qhov chaw txuas rau carbohydrates, hlau lossis vitamins. Kev tsim cov qauv tertiary lossis quaternary ua rau nws tuaj yeem nrhiav tau ntau qhov chaw rau cov pab pawg nkag. Qhov no tso cai rau koj los tsim los ntawmprotein derivative uas plays lub luag hauj lwm ntawm ib tug enzyme, receptor, carrier ntawm cov khoom mus rau hauv los yog tawm ntawm ib tug cell, immunoglobulin, structural tivthaiv ntawm ib daim nyias nyias los yog cell organelle, nqaij protein.
Proteins, tsim los ntawm cov amino acids, tsuas yog lub hauv paus ntawm lub neej. Thiab niaj hnub no nws ntseeg tau hais tias lub neej tsuas yog tshwm sim tom qab cov tsos ntawm cov amino acid thiab raws li ib tug tshwm sim ntawm nws cov polymerization. Tom qab tag nrho, nws yog kev sib cuam tshuam ntawm cov proteins uas yog qhov pib ntawm lub neej, suav nrog lub neej ntse. Tag nrho lwm cov txheej txheem biochemical, suav nrog cov khoom siv hluav taws xob, yog qhov tsim nyog rau kev siv cov protein biosynthesis, thiab vim li ntawd, qhov txuas ntxiv ntawm lub neej.
