Integral Proteins vs Peripheral Proteins
Proteins yog suav tias yog macro molecules, uas muaj ib los yog ntau dua polypeptide chains. Cov saw hlau polypeptide yog tsim los ntawm cov amino acids sib koom ua ke los ntawm peptide bonds. Cov qauv tseem ceeb ntawm cov protein tuaj yeem txiav txim siab los ntawm cov amino acid ib ntus. Qee cov noob code rau ntau cov proteins. Cov noob no txiav txim siab qhov sib lawv liag ntawm cov amino acid, yog li txiav txim siab lawv cov qauv tseem ceeb. Integral thiab peripheral proteins raug suav hais tias yog 'plasma membrane proteins' vim lawv qhov tshwm sim. Cov proteins no feem ntau yog lub luag haujlwm rau lub cell lub peev xwm los cuam tshuam nrog ib puag ncig sab nraud.
Integral Protein
Cov proteins ib txwm muaj feem ntau pom muaj tag nrho lossis ib nrab hauv dej hauv phospholipids bilayer ntawm plasma membrane. Cov proteins no muaj ob qho tib si polar thiab tsis-polar cheeb tsam ntawm lawv. Polar taub hau protrude los ntawm qhov chaw ntawm lub bilayer thaum lub cheeb tsam uas tsis yog-polar yog embedded nyob rau hauv nws. Feem ntau tsuas yog cov cheeb tsam uas tsis yog-polar cuam tshuam nrog cov tub ntxhais hydrophobic ntawm cov plasma membrane los ntawm kev ua hydrophobic bonds nrog fatty acid tails ntawm phospholipids.
Cov proteins ib txwm muaj uas nthuav tawm tag nrho daim nyias nyias los ntawm sab hauv mus rau sab nrauv yog hu ua transmembrane proteins. Nyob rau hauv transmembrane proteins, ob qho tag nrho qhov project tawm ntawm lipid txheej yog polar los yog hydrophilic cheeb tsam. Cov cheeb tsam nruab nrab yog tsis-polar thiab muaj hydrophobic amino acids ntawm lawv qhov chaw. Peb hom kev sib cuam tshuam pab kom embed cov proteins nyob rau hauv lipid bilayer, uas yog, ionic kev sib cuam tshuam nrog lub ncov qaumteb qabteb taub hau ntawm phospholipid molecules, hydrophobic kev sib tshuam nrog cov hydrophobic tails ntawm phospholipid molecules thiab kev sib cuam tshuam nrog qee thaj tsam ntawm lipids, glycolipids lossis oligosac.
YPeripheral Protein
Peripheral proteins (extrinsic proteins) muaj nyob rau sab hauv thiab sab nraud ntawm phospholipids bilayer. Cov proteins no tau xoob khi rau cov plasma membrane ncaj qha los ntawm kev sib cuam tshuam nrog lub taub hau ntawm phospholipids bilayer lossis tsis ncaj los ntawm kev sib cuam tshuam nrog cov protein. Cov proteins no muaj li ntawm 20-30% ntawm tag nrho cov membrane proteins.
Feem ntau ntawm cov proteins peripheral muaj nyob rau ntawm qhov chaw sab hauv lossis cytoplasmic ntawm daim nyias nyias. Cov proteins no tseem muaj kev cuam tshuam los ntawm kev sib txuas ntawm covalent bonds nrog fatty chains lossis los ntawm oligosaccharide rau phospholipids.
Qhov txawv ntawm Integral thiab Peripheral Protein yog dab tsi?
• Peripheral proteins tshwm sim nyob rau saum npoo ntawm plasma membrane thaum cov proteins ib txwm tshwm sim tag nrho los yog ib nrab submerged nyob rau hauv lipid txheej ntawm plasma membrane.
• Peripheral proteins yog xoob khi rau lipid bilayer thiab tsis cuam tshuam nrog hydrophobic core nyob nruab nrab ntawm ob txheej ntawm phospholipids. Hauv qhov sib piv, cov proteins ib txwm yog nruj nruj thiab cuam tshuam ncaj qha nrog cov tub ntxhais hydrophobic ntawm plasma membrane. Vim yog cov laj thawj no, kev sib koom ua ke ntawm cov protein ntau yog qhov nyuaj dua li cov proteins peripheral.
• Kev kho mob me me tuaj yeem siv los cais cov kab mob peripheral los ntawm cov ntshav plasma, tab sis rau kev sib cais ntawm cov protein ntau, kev kho mob me tsis txaus. Txhawm rau rhuav tshem cov ntawv cog lus hydrophobic, cov tshuaj detergents yuav tsum tau ua. Yog li, cov proteins ib txwm tuaj yeem raug cais tawm ntawm plasma membrane.
• Tom qab kev sib cais ntawm ob cov proteins los ntawm cov plasma membrane, peripheral proteins tuaj yeem yaj hauv nruab nrab aqueous buffers thaum cov proteins tsis tuaj yeem yaj hauv nruab nrab aqueous buffers lossis aggregates.
• Tsis zoo li peripheral proteins, integral proteins yog txuam nrog lipid thaum solubilized.
• Piv txwv ntawm peripheral proteins yog spectrin ntawm erythrocytes, cytochrome C thiab ATP-ase ntawm mitochondria thiab acetylcholinesterase nyob rau hauv electroplax membranes. Piv txwv ntawm cov proteins ib txwm yog cov membrane bounded enzymes, tshuaj thiab cov tshuaj hormones, antigen thiab rhodopsin.
• Cov proteins ib txwm sawv cev ib puag ncig 70% thaum cov proteins peripheral sawv cev rau qhov seem ntawm cov plasma membrane proteins.
