Ama-Hexose awuhlobo lwe-monosaccharide equkethe ama-athomu e-carbon ayisithupha esakhiweni sawo samangqamuzana. Atholakala kakhulu emvelweni futhi adlala indima ebalulekile kumetabolism yamaselula. Ama-hexose angumthombo obalulekile wamandla kumaseli, ahlehliswa ngokushesha nge-glycolysis ukuze akhiqize i-ATP. Ngaphezu kwalokho, ama-hexose nawo ayizingxenye zesakhiwo sama-carbohydrate amaningi ayinkimbinkimbi, njenge-polysaccharides. Imikhiqizo eminingana ye-hexose yenza imisebenzi ethile emzimbeni, njengama-nucleotide kashukela asetshenziswa ekuhlanganiseni ama-nucleic acid nama-glycoprotein.
Izici eziyinhloko zama-monosaccharides: funda kabanzi mayelana nala ma-molecule abalulekile ekudleni.
Ama-monosaccharides ama-carbohydrate alula, akhiwe i-molecule eyodwa kashukela. Ziwuhlobo oluyisisekelo kakhulu lwe-carbohydrate futhi amuncwa kalula ngumzimba. Esinye sezici eziyinhloko zama-monosaccharides ukumuncwa kwawo ngokushesha ngumzimba, kunikeze amandla ngokushesha.
Enye ye-hexose evame kakhulu i-glucose, edlala indima ebalulekile kumetabolism yamandla eselula. IGlucose ingumthombo oyinhloko wamandla obuchopho nemisipha futhi ibalulekile ekusebenzeni kahle komzimba.
Ngaphandle kweglucose, enye i-hexogen ebalulekile i-fructose, etholakala ezithelweni noju. I-Fructose imnandi kuneglucose futhi isetshenziswa njenge-sweetener emikhiqizweni ehlukahlukene. Iphinde imuncwe ngokushesha ngumzimba, inikeze amandla asebenzayo.
Ama-hexose nawo angatholakala kokuphuma kwamanye ama-monosaccharides, njenge-galactose, eyingxenye yobisi. I-galactose iguqulwa ibe ushukela esibindini futhi isetshenziswa njengomthombo wamandla ngumzimba.
Badlala indima ebalulekile kumetabolism futhi batholakala ekudleni okuhlukahlukene, okubenza babaluleke ekudleni okunomsoco nokunempilo.
Imisebenzi ye-Organic ye-monosaccharides: lokho abayikho kanye nezici zabo eziyinhloko.
Ama-monosaccharides ama-carbohydrate alula akhiwa i-molecule eyodwa kashukela. Benza imisebenzi ehlukahlukene ye-organic emzimbeni futhi ibalulekile ekusebenzeni kahle. Phakathi kwe-monosaccharides eyinhloko, hexosa, enama-athomu ekhabhoni ayisithupha ekwakhekeni kwawo.
I-Hexoses iyisigaba esibaluleke kakhulu sama-monosaccharides, akhona ngezindlela ezihlukahlukene eziphilayo. I-glucose ne-fructose yizibonelo zama-hexoses atholakala kabanzi emvelweni. IGlucose iwumthombo oyinhloko wamandla amangqamuzana, kuyilapho i-fructose ikhona ezithelweni noju, iwumthombo obalulekile wokunambitheka okumnandi.
Ngaphezu kwemisebenzi yawo enamandla, ama-hexose angasetshenziswa futhi ekuhlanganiseni amanye ama-molecule ephilayo, njengama-lipids namaprotheni. Babamba iqhaza ngenkuthalo kumetabolism yamaselula, banikeze amandla nama-substrates ezindleleni ezahlukahlukene ze-metabolic.
Ama-Hexoses angabhekana nokuguqulwa okuningana emaqenjini abo asebenzayo, okuholela okukhishwa ngezakhiwo ezithile. Isibonelo, i-galactose iphuma ku-glucose edlala indima ebalulekile ekwakhekeni kwama-glycoprotein nama-glycolipids akhona kulwelwesi lwamaseli.
Okuphuma kuzo nakho kubalulekile emisebenzini ehlukahlukene yezinto eziphilayo, okubonisa ukubaluleka kwalezi zinhlanganisela ku-physiology yezidalwa eziphilayo.
Izinhlobo zama-monosaccharides: imindeni ehlukene namaqembu amakhemikhali.
Ama-monosaccharides ama-carbohydrate alula akhiwa i-molecule eyodwa kashukela. Kunezinhlobo ezahlukene zama-monosaccharides, ezingahlukaniswa zibe imindeni eminingana ngokwamaqembu awo ahlukene amakhemikhali. Enye yezinhlobo ezivame kakhulu zama-monosaccharides hexosa, enama-athomu e-carbon ayisithupha esakhiweni sawo samangqamuzana.
Ama-hexose atholakala ekudleni okuhlukahlukene, njengezithelo, uju, neminye imifino. Badlala indima ebalulekile ekugayweni kwamandla emzimbeni, banikeze umthombo wamandla obalulekile kumaseli. Ngaphezu kwalokho, ama-hexose nawo abandakanyeka ekuhlanganiseni ama-glycoprotein, glycolipids, nama-nucleic acid.
Ezinye izibonelo ze-hexoses zihlanganisa i-glucose, i-fructose, ne-galactose. IGlucose inguphethiloli oyinhloko wamangqamuzana futhi ibalulekile ekusebenzeni kobuchopho nemisipha. I-Fructose ushukela otholakala ngokwemvelo esithelweni, kanti i-galactose itholakala obisini nasemikhiqizo yobisi.
Ngaphezu kwama-hexasaccharides, kunezinye izinhlobo ze-monosaccharides, njenge pentosas e njengoba ama-triose, ngasinye sinezici ezithile nemisebenzi emzimbeni. Kodwa-ke, ama-hexose awaningi kakhulu futhi aziwa kakhulu, adlala indima ebalulekile ekudleni komuntu kanye ne-metabolism.
Ukuhlukaniswa kwama-monosaccharides ngokweqembu elisebenzayo elikhona kuma-molecule awo.
Ama-monosaccharides angahlukaniswa ngokweqembu elisebenzayo elikhona kuma-molecule awo. Kunamaqembu amathathu asebenzayo: ama-aldehydes, ama-ketones e utshwala.
Ama-monosaccharides aneqembu elisebenzayo i-aldehyde babizwa ama-aldoses, kuyilapho labo abaneqembu elisebenzayo cetona babizwa ama-ketoses. Ama-monosaccharides aneqembu elisebenzayo utshwala babizwa ama-polyols.
I-Hexosa: izici, imisebenzi, i-derivatives
As i-hexagonal ziwuhlobo lwe-monosaccharide enama-athomu e-carbon ayisithupha ku-molecule yawo. Badlala indima ebalulekile kumetabolism yamandla amangqamuzana, abe umthombo obalulekile wamandla emzimbeni.
Ngaphezu kwendima yabo njengomthombo wamandla, ama-hexose nawo adlala indima ebalulekile ekwakhekeni kwezakhiwo zamaselula, njengezindonga zamaseli ezitshalo. Baphinde babambe iqhaza ekuboniseni amaseli kanye nokuxhumana phakathi kwamaseli.
Ama-hexose angatholakala ekudleni okuhlukahlukene, njengezithelo, uju, nama-syrups. Angabuye athathwe ukuze akhiqize ezinye izinhlanganisela, njenge-ascorbic acid (uvithamini C) kanye ne-hyaluronic acid, ebalulekile empilweni nokusebenza komzimba.
I-Hexosa: izici, imisebenzi, i-derivatives
Uma hexose i-carbohydrate enama-athomu ekhabhoni ayisithupha futhi ifomula yayo yokuqina ingu-C 6 H 12 O 6 . Ama-carbohydrate noma ama-saccharides (kusuka kwesiGreki sakcharon = ushukela) ziyi-polyhydroxy aldehydes noma i-polyhydroxy ketones.
Emvelweni, i-monosaccharide eningi kakhulu i-glucose, ushukela we-carbon ayisithupha, obizwa nangokuthi i-dextrose. I-biosynthesis yeglucose ivela ku-carbon dioxide namanzi ngokusebenzisa i-photosynthesis.
Ezitshalweni, i-glucose iwukuhlanganiswa kwe-cellulose, i-polysaccharide yesakhiwo, kanye nesitashi, i-polysaccharide egciniwe. Ezakhiweni ze-heterotrophic, i-glucose oxidation iyindlela eyinhloko ye-metabolic yokukhiqiza amandla.
Izici
Ama-Hexoses angaba yizinhlobo ezimbili: 1) ama-aldoses (noma ama-aldohexoses), lapho i-carbon 1 (C-1) ingumsebenzi we-aldehyde; noma 2) ama-ketose (noma ama-aldoketose) lapho i-carbon 2 (C-2) ingumsebenzi we-keto. Amakhabhoni asele angama-alcohol esibili noma ayisisekelo.
Ku-aldohexoses, wonke amakhabhoni ayi-chiral ngaphandle kwe-carbon 1 (C-1) ne-carbon 6 (C-6), okusho ukuthi anezikhungo ezine ze-asymmetric. Ku-ketohexoses, kunezikhungo ezintathu ze-asymmetric: C-3, C-4, ne-C-5.
Ngokwemvelo, ushukela onjengama-hexose anokumiswa kwe-L awuningi kakhulu kunoshukela onokucushwa kuka-D.
Umsebenzi we-aldehyde noma we-keto wama-hexoses uhlangana neqembu lesibili le-hydroxyl ngokusabela kwe-intramolecular ukwakha i-hemiacetals noma i-cyclic hemiketals. Ushukela we-cyclic onamalungu ayisithupha ama-pyranose, kanti lawo anamalungu amahlanu angama-furanose.
Kushukela we-cyclic, i-carbonyl carbon ye-aldehyde namaqembu e-keto iba isikhungo esisha se-chiral, esibizwa nge-anomeric carbon. Le khabhoni ingalungiselelwa ekucushweni kwe-alpha noma kwe-beta, ikhiqize ama-anomer amabili.
Ama-hexoses anezinhlobonhlobo ezahlukene
Ama-athomu ayisithupha akha i-pyranose awawona amapulani, kodwa anokwakheka okubili okufana nesihlalo lapho okukhona okubambe iqhaza okukhulu: a) izindawo zenkabazwe noma b) izindawo ze-axial. Lokhu kuhlanganisa kungashintshana ngaphandle kokwephula amabhondi e-covalent.
Ukusebenzisana kwamakhemikhali e-stereochemical phakathi kwama-ring substitutes kuthonya ukuzinza okuhlobene kwalokhu kuhlanganisa. Ngakho-ke, i-conformation ezime kakhulu yileyo lapho iqembu elikhulu kakhulu lithatha indawo yenkabazwe.
Ukusebenza kabusha kwamakhemikhali kweqembu elithile kuthonywa indawo yalo ehambisanayo. Isibonelo yiqembu le-hydroxyl (-OH), okuthi, uma lisendaweni yenkabazwe, libe ne-esterified kalula kunalapho lihlezi endaweni ye-axial.
O β -D-glucose, i-aldohexose, inazo zonke izithako zayo endaweni yenkabazwe, okwenza kube lula ukungenwa yi-esterification. Lokhu kusabela kubalulekile ekwakhekeni kwezibopho ezihlangene phakathi kukashukela. Lokhu kungachaza ukuthi kungani β I-D-glucose ingushukela omningi kakhulu emvelweni.
Ama-Hexoses angakha amabhondi e-glycosidic
Amayunithi e-Monosaccharide, njengama-hexoses, angaxhunyaniswa ngokuhlanganyela ngamabhondi e-O-glycosidic akhiwe lapho i-anomeric carbon ye-molecule eyodwa kashukela isabela neqembu le-hydroxyl lenye i-molecule kashukela. Umphumela walokhu kusabela ukwakheka kwe-acetal evela ku-hemiacetal.
Isibonelo ukusabela kwe-C-1 anomeric carbon ye-α-D-glucopyranoside neqembu le-C-4 hydroxyl lenye. β -D-glucopyranoside. Ifomu α -D-glucopyranosyl- (1®4) -D-glucopyranoside.
Ukusabela kwe-glycosidic bond formation kuhilela ukususwa kwe-molecule yamanzi, ebizwa ngokuthi i-condensation reaction. Ukusabela okuphambene yi-hydrolysis kanye nokuphuka kwebhondi ye-glycosidic.
Hexoses kanye oxide ukunciphisa ukusabela
Oshukela abane-athomu yekhabhoni ye-anomeric engazange akhe amabhondi e-glycosidic abizwa ngokuthi ushukela okwehlisa. Wonke ama-monosaccharides, njenge-hexoses ye-glucose, i-mannose, ne-galactose, anciphisa ushukela. Lokhu kungenxa yokuthi ama-aldose noma ama-ketose anganikela ngama-electron, noma anciphise, kumsebenzeli oxidizing.
Ukuhlolwa okujwayelekile kokunciphisa ushukela kwenziwa nge-Fehling (noma i-Benedict) nama-reagents e-Tollens. Isibonelo, ushukela owehlisayo unganciphisa i-Ag + etholakala kusixazululo se-ammonium (i-Tollens' reagent). Lokhu kusabela kukhiqiza isiliva lensimbi ngaphansi komkhumbi lapho ukusabela kwenzeke khona.
Ngokusabela okwenziwa i-enzyme glucose oxidase, i-anomeric carbon ye-D-glucose i-oxidized, ilahlekelwe ipheya lama-electron, futhi umoya-mpilo uyancishiswa, uthole ipheya lama-electron. Lokhu kusabela kukhiqiza imikhiqizo emibili: D-glucono- d - i-lactone ne-hydrogen peroxide.
Njengamanje, ukugcwala kweglucose egazini kunqunywa ukuhlolwa okusebenzisa i-glucose oxidase ne-peroxidase. I-enzyme yokugcina idala ukusabela kokunciphisa i-oxidation.
Ama-substrates e-peroxidase yi-hydrogen peroxide kanye nento e-chromogenic, ekhishwa nge-oxidized. Lokhu kusabela kungalinganiswa kusetshenziswa i-spectrophotometer.
I-Hexose derivatives
Kuningi okuphuma kokunye okuphuma ku-hexose okuneqembu le-hydroxyl elithathelwa indawo enye esikhundleni. Isibonelo, iqembu le-C-2 hydroxyl le-glucose, i-galactose, ne-mannose lithathelwa indawo iqembu le-amino, lakhe i-glucosamine, i-galactosamine, ne-mannosamine, ngokulandelanayo.
Iqembu lama-amino livame ukuhlangana ne-acetic acid, lenze i-N-acetylglucosamine. Lokhu okuphuma ku-glucosamine kutholakala ezindongeni zamangqamuzana amagciwane.
Okuphuma ku-N-acetylmannosamine yi-N-acetylneuraminic acid, eyaziwa nge-sialic acid. I-Sialic acid ikhona kuma-glycoprotein nama-glycolipids ebusweni bamaseli, idlala indima ekubonweni kwamaseli.
I-oxidation ethize yeqembu lokuqala lotshwala, i-C-6, ye-aldohexose glucose, i-galactose, ne-mannose ikhiqiza ama-uronic acid. Le mikhiqizo i-D-glucuronic acid, i-D-galacturonic acid, ne-D-mannuronic acid, etholakala kuma-polysaccharides amaningi.
Ama-Uronic acid angangena kwi-intramolecular esterification, enze ama-lactone ama-athomu amahlanu noma ayisithupha. Isibonelo, i-ascorbic acid (uvithamini C) ihlanganiswa izitshalo.
Ukushintsha iqembu le-hydroxyl (-OH) nge-athomu ye-hydrogen ku-C-6 ye-L-galactose noma i-L-mannose kukhiqiza i-L-fucose noma i-L-rhamnose, ngokulandelanayo. I-L-fucose itholakala kuma-glycoprotein nama-glycolipids. I-L-rhamnose itholakala kuma-polysaccharides ezitshalweni.
Ama-hexose ajwayelekile kakhulu emvelweni nemisebenzi yawo
IGlucose
Uphawu: Glc. I-aldohexose noma i-glucohexose. I-D-glucose enantiomer (uphawu D-Glu) ivame kakhulu kune-L-Glc enantiomer. I-D-Glc ikhona ezitshalweni, uju, amagilebhisi, negazi lezilwane. Iwumthombo wamandla ezidalwa eziphilayo. Isebenza njengesandulela sokuhlanganiswa kwe-glycogen, i-cellulose, isitashi, ne-lactose.
UFructose
Uphawu: Fru. I-ketohexose noma i-fructohexose. I-enantiomer ye-D-fructose yaziwa kakhulu ngokuthi i-fructose. Lo shukela utholakala, isibonelo, ezithelweni, uju, nesidoda.
IGalactose
Uphawu Gal. I-aldohexose noma i-galatohexose. I-D-galactose ivame kakhulu kune-L-galactose. I-D-galactose ingushukela ebuchosheni, noma ushukela wobuchopho. Akuvamile ukutholakala mahhala. Ivame ukutholakala ezitshalweni, ezilwaneni, nasezintweni ezincane ezincane ezifana nama-oligosaccharides nama-polysaccharides.
umnono
Uphawu: Indoda. I-aldohexose noma i-mannohexose. Ifomu le-D-mannose lisatshalaliswa kabanzi kumana kanye ne-hemicellulose. Itholakala njenge-oligosaccharide exhunywe ku-N kuma-glycoprotein, akha amagatsha.
I-Rhamnose
Uphawu: Rha. Kuyi-aldohexose etholakala kuma-glycosides ezitshalo, ku-gum kanye ne-mucilage polysaccharides, kanye nasezindongeni zamaseli ezitshalo nama-flavonoid.
Izinkomba
- Cui, SW 2005. Ama-carbohydrates okudla: amakhemikhali, izakhiwo zomzimba kanye nezicelo. CRC Cindezela, Boca Raton.
- Nelson, DL, Cox, MM 2017. Izimiso zikaLehninger ze-biochemistry. U-WH Freeman, eNew York.
- Rastall, RA 2010. Ama-oligosaccharides asebenzayo: ukusetshenziswa nokukhiqiza. Ukubuyekezwa Konyaka Kwesayensi Yokudla Nobuchwepheshe, 1, 305–339.
- Sinnott, M. L. 2007. Isakhiwo kanye nendlela ye-carbohydrate chemistry kanye ne-biochemistry. I-Royal Society of Chemistry, eCambridge.
- Stick, RV, Williams, SJ 2009. Ama-carbohydrate: ama-molecule abalulekile wokuphila. Elsevier, Amsterdam.
- Tomasik, P. 2004. Izakhiwo zamakhemikhali nezisebenzayo zama-saccharides okudla. CRC Cindezela, Boca Raton.
- Voet, D., Voet, J.G., Pratt, C.W. 2008. Okuyisisekelo kwe-biochemistry - ukuphila ezingeni lamangqamuzana. Wiley, Hoboken.