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Binding protein



Synonymousbindingproteingenerallyreferstobindingprotein

Definition

Inadditiontoaminoacidcomponents,themoleculeofbindingproteinalsocontainsnon-aminoacidsubstances.Thelatteriscalledcofactor.Combinationinvalenceornon-covalentformisoftenseparatedfromthebiologicalmaterialasawhole.Simpleproteinreferstothemolecularcomposition,exceptforthepolypeptideproteincomponentcomposedofaminoacids,withoutanynon-proteincomponentscalledpureprotein.Manyproteinsinnaturefallintothiscategory.Thebindingproteinisacombinationofasimpleproteinandothercompounds,andothercompoundsthatareboundareusuallycalledthenon-proteinpart(prostheticgroup)ofthebindingprotein.Accordingtothedifferentnon-proteinparts,itisdividedintonucleoprotein(containingnucleicacid),glycoprotein(containingpolysaccharide),lipoprotein(containinglipid),phosphoprotein(containingphosphoricacid),metalloprotein(containingmetal)andchromoprotein(containingPigment)andsoon.

Classification

Bindingproteinsaremainlydividedintothefollowingcategories.Chromoprotein:Thecombinationofproteinandpigmentmaterial,suchashemoglobin.Lecithin:Proteiniscombinedwithlecithin,suchasfibrinandvitellinintheblood.Lipoprotein:solubleinwater,itisacombinationoffatandprotein.Lipoproteinisatoolforthebodytotransportfatinthebody.Includingchylomicrons,verylow-densitylipoproteins,low-densitylipoproteins,andhigh-densitylipoproteins.Metalloproteins:Proteinsbindtometals,suchastransferrinandcopper-zincbindingprotein.Manyenzymescontainmetalions.Mucinorglycoprotein:Aproteincontainingcarbohydratessuchasmannoseandgalactose.Themucussecretedbyhumancelltissuescontainsmucin.Nucleoprotein:Theproteinbindstonucleicacid,andthenucleoproteinexistsintissueembryosandglandulartissuesofthehumanbody.

Glycoproteins

Proteinscovalentlyboundtocarbohydrates,containinglessthan4%sugar.Glycosylsincludedisaccharides,oligosaccharidesandpolysaccharides.Glycoproteinisaverycomplextypeofproteinwithmanytypes,suchas:bloodgroupglycoprotein,hormoneglycoprotein,cellmembraneglycoprotein,ovalbumin,andexogenouslectin.

Mucoprotein(mucoprotein)

Aproteinthatbindstoaminopolysaccharidesandcontainslessthan4%sugar.Generallycontainβ-glucosamine,whichisboundtooneormoreofthefollowingsugars:galactose,mannose,rhamnose,glucuronicacid,etc.

Nucleoprotein(nucleoprotein)

Proteinsthatbindtonucleicacids.Suchas:DNAnucleoprotein,ribosome,simpleplantvirus,etc.Nucleoproteinexistsinallorganisms,andthecytoplasmandnucleuscontainnuclearprotein.

Lipoprotein(lipoprotein)

Abindingproteincomposedofproteinandfatorlipids.Lipoproteinsarewidelypresentinanimals.Thelipoproteinsinthebloodofhigheranimalsincludeα-lipoproteinandβ-lipoprotein.Thelipoproteininthecellmembraneaffectsthepermeabilityofthecellmembrane.

Phosphoproteins

Proteinscovalentlyboundtophosphate.Phosphoricacidbindstothesidechainhydroxylgroupofserineorthreonineofprotein,andhasdissociableacidicgroups,whichmainlyexistineggyolkandmilk.Suchas:casein(casein),pepsin(pepsin).

Metaoproteins

Proteinsthatdirectlybindtometalions.Forexample,ferritincontainsFe2+,nitrogenasecontainsMo2+andFe2+,andcarboxypeptidasecontainsZn2+,superoxidedismutasecontainsCu2+andZn2+,etc.Manyproteinscontainasmallamountofmetal.

Hemoprotein(hemoprotein)

Theproteinthatbindstotheprostheticgroupheme,whosemainfunctionistoparticipateinrespirationoroxygentransport.Suchas:hemoglobinofhigheranimals,hemocyaninofloweranimals,inadditionto:chlorophyll,catalase,myoglobinandsoon.

Flavoproteins

ProteinsthatbindtotheflavoproteinsFADorFMN.Suchas:flavodoxin,D-aminoacidoxidase,etc.

Importantbindingprotein

Hemoglobin

Hemoglobinisachromoproteinmainlyfoundinvertebrateredbloodcells.ItsmainfunctionistoThehumanbodycarriesoxygenandcarbondioxide.In100mlwholebloodofanormalhumanbody,hemoglobinis12-16g.Theironcontentofhumanhemoglobinisabout0.33%to0.34%,anditsrelativemolecularmassisabout67000.Hemoglobiniscomposedofglobinandprostheticheme.Itscompositionvariesfromdifferentsources,andthedifferenceisonlyintheglobinpart.

Theglobininhemoglobinisaproteinwithaquaternarystructurecomposedof4peptidechains.Eachofthese4peptidechainsbindsto1heme,andeachhemecanbindto1oxygenmolecule,so1hemoglobinmoleculecanbind4oxygenmolecules.Thistypeofproteiniscalledoxygenation.Hemoglobin.Oxyhemoglobinisveryunstable,anditsbindingforcewithoxygenoftenchangeswiththelevelofoxygenpartialpressure.Hemoglobintransportsoxygenthroughsuchanoxygenationreaction.

Theglobininhemoglobininnormaladultsiscomposedoftwoidenticala-peptidechainsandtwoidenticalpeptidechains,whichcanbeuseda2β2iscalledhemoglobinAandisrepresentedbyHbA.Adultscontain96%HbAand0.5~4%HbA2.ThecompositionofHbA2isa2β2.FetalhemoglobinismainlyHbF,anditscompositionisa2γ2.Thesequenceoftheaminoacidresiduesofa,β,γ,andδpeptidechainshasbeendeterminedbydetermination.Amongthem,theα-peptidechainiscomposedof141residues,andtheβ,γ,andδpeptidechainsareallcomposedof146residues.Theirprimarystructureisdifferent,butthesecondaryandtertiarystructuresareverysimilar.

Nucleoprotein

Nucleoproteiniscallednucleoproteinbecauseitisoriginallyfoundinthenucleus.Itisabindingproteininthecell.Boththenucleusandthecytoplasmcontainnuclearproteins.Inaddition,nucleoproteinsarealsocontainedinviruses,chromosomesandnucleoproteinbodies.Nuclearegghasauniquefunctionandroleinthegrowthandreproductionprocessoflivingorganisms.

Nucleoproteiniscomposedofcationicbasicprotein(suchashistoneandprotamine)andproteinprostheticgroup(nucleicacid).Histonescontainbasicaminoacids(suchaslysineandarginine),sotheyarebasic.Itsrelativemolecularmassis11000to21000.Protamineispresentinsomeprotaminenucleoproteins,andbecauseitisrichinarginine,itisalsoalkaline.

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