Kunjani ukwakheka kwe-cholesterol esibindini?

Njengombana into le ingeyohlobo lwama-alcohols, igama elithi "cholesterol" lilo lodwa elisebenzayo, kuyilapho igama elithi "cholesterol" (ngokoqobo "i-bile eqinile" ngenxa yokuhlukaniswa kwalo kwasekuqaleni kwama-gallstones) labelwa isizinda ngesiko - okokuqala elatholwa ngo-1769 ngusokhemisi waseFrance uPouletier de I-La Sal, ikhombisile izakhiwo ezisobala zamafutha, lapho ibibalwa khona ekuqaleni.

Ngenxa yamaphutha athile ososayensi, i-cholesterol kwathiwa "isitha No. 1" impilo yomzimba iminyaka eminingi, okubangele inguquko yangempela embonini yokudla, ekhemisi nezindlela zokwelashwa - kanye nemikhiqizo yamafutha aphansi, izidakamizwa nezindlela ezintsha ezavela emhlabeni ezinganciphisa kakhulu ukugxila kuhlanganiswa egazini, nakho konke lokhu - namadivayisi okulawula we- "pest" ukuze ihlale ihlolwe.

Njengoba indlela enhle yokubheka ukulimala kwento eyodwa noma enye kuyindlela yokukususa ekujikelezeni, lokhu sekwenziwe - njengomphumela, umhlaba wonke manje uvuna izithelo eziyinhlekelele "zokudla okuhlisiwe", futhi ososayensi bayaphoqelelwa ukuthi benze izaba futhi bathembisa ukukulungisa. Kepha lokhu kungenziwa kuphela ngokuqonda umsuka nendima yangempela yento emzimbeni.

Imisebenzi esemqoka ye-cholesterol

Ngaphezu kweqiniso lokuthi liyisakhi esisemqoka (fluidity stabilizer) se-cytoplasmic membrane, ukuqinisekisa ukuqina kwesendlalelo sayo esiphindwe kabili ngenxa yokubekeka okuningana kwamangqamuzana we-phospholipid, i-cholesterol iziveza njengesici-somlawuli wokuvuma kokuqanjwa kwamaseli weseli, kuvimbele ukuvuvukala kwegazi. .

Iphinde isebenze njengesiqalo sokukhiqizwa kwamakhemikhali weqembu le-steroid:

• amahomoni e-corticosteroid;
• ama-hormone ocansi;
• ama-bile acid;
• Amavithamini e-D-group (ergocalciferorol ne-cholecalciferol).

Njengoba kunikezwe ukubaluleka komzimba weqembu ngalinye lalezinto, kuba sobala ukulimala kokudla okungenayo i-cholesterol noma ukwehla okwenziwe ngamazinga entweni yaleli gazi.

Ngenxa yokuntuleka kwayo emanzini, le nto ingahanjiswa ngegazi kuphela ngokuhambisana namaprotheni ama-transporter (ama-apolipoproteins), lapho kuhlanganiswa nokwakhelwa khona izakhi eziyinkimbinkimbi ze-lipoprotein.

Ngenxa yokuba khona kwama-apolipoproteins amaningi ahlukene (nomehluko kwesisindo samangqamuzana, isilinganiso sawo se-tropism se-cholesterol, futhi futhi ngenxa yekhono lenkimbinkimbi yokuqothula egazini, kanye nezindawo eziphikisayo zamakristali e-cholesterol ukwakha ama-atherosranceotic plaques), lezi zigaba ezilandelayo ze-lipoproteins ziyahlukaniswa:

• ukushuba okuphezulu (i-HDL, noma isisindo esikhulu samangqamuzana, noma i-HDL-lipoproteins);
• ukungazweli okuphansi (i-LDL, noma isisindo esisezingeni eliphansi, noma i-LDL-lipoproteins);
• kwabantu abaphansi kakhulu (i-VLDL, isisindo esisezingeni eliphansi ngokweqile, noma isigaba se-VLDL sama-lipoprotein);
• chylomicrons.

Ezithanjeni zomngcelezi, i-cholesterol ingena iboshelwe kuma-chylomicrons, i-LDL noma i-VLDL, esibindini (ngokususwa kamuva komzimba) - ngokuhambisa ama-apolipoproteins esigabeni se-HDL.

Izici Zokubukeka

Ukuze noma yiziphi izingqimba ze-atherosulinotic zenze kusuka ku-cholesterol (okwenzeka ngasikhathi sinye kube “yimigqa” odongeni lomthambo olonakele, kanye “nezikhala” zangaphakathi endaweni lapho ngaphandle kwazo ukufinyeleleka kwengqimba yomsipha kufanele kuholele ekubulalekeni kwayo - isayithi liwela), noma ama-hormone, noma eminye imikhiqizo, yona emzimbeni kufanele ihlanganiswe kuqala kwenye yezindawo ezintathu:

• isikhumba
• amathumbu;
• isibindi.

Njengoba amaseli wesibindi (i-cytosol yabo kanye ne-endiclopic reticulum ebushelelezi) engabanikezeli abaphambili besakhiwo (ngo-50% noma ngaphezulu), ukwakheka kwento kufanele kubhekwe ngokuqondile ngokombono wokuphendula okwenzeka kuwo.

Ukuvela kwe-cholesterol kwenzeka ngezigaba ezi-5 - ngokwenziwa okulandelanayo:

• i-mevalonate;
• isopentenyl pyrophosphate;
• squalene;
• i-lanosterol;
• empeleni cholesterol.

Uguquko oluningi belungeke lube khona ngaphandle kokubamba iqhaza kwama-enzyme okuvusa isigaba ngasinye senqubo.

Ividiyo ekwakhekeni kwe-cholesterol:

Izinduna ezithintekayo ekwakhiweni kwendaba

Esigabeni sokuqala (okubandakanya imisebenzi emithathu), ukudalwa kwe-acetoacetyl-CoA (lapha iCoA - coenzyme A) kuqalwa yi-acetyl-CoA-acetyltrasferase (thiolase) ngokuhlanganiswa kwama-molecule ama-2 acetyl-CoA. Ngaphezu kwalokho, ngokubamba iqhaza kwe-HMG-CoA synthase (i-hydroxymethyl-glutaryl-CoA synthase), ukuvela kusuka ku-acetoacetyl-CoA kanye nenye i-molecule ye-acetyl-CoA ꞵ-hydroxy-ꞵ-methylglutaryl-CoA kungenzeka.

Lapho kuncishiswa i-HMG (ꞵ-hydroxy-ꞵ-methyl-glutaryl-CoA) ngokuqothuka kwesicucwana se-HS-CoA ngokubamba iqhaza kwe-NADP-hydroxymethyl-glutaryl-CoA reductase (HMG-CoA reductase), umkhiqizo wokuqala ophakathi, i-cholesterol preursor. )

Esigabeni sokuhlanganiswa kwe-isopentinyl pyrophosphate, imisebenzi emine yenziwa. Ngama-mevalonate kinase (bese kuba yi-phosphomevalonate kinase), iMevalonate iguqulwa ibe yizi-5-phosphomevalonate ku-1 no-2 Mevalonate kinase (bese iphosphomevalonate kinase), bese iya ku-5-pyrophosphomevalonate, eba yi-3-phospho-5-pyrophosphomephostionate 3 phphophosphomephostionate. (ngokubamba iqhaza kwe-enase yama-kinase).

Umsebenzi wokugcina yi-decarboxylation kanye ne-dephosphorylation ngokwenziwa kwe-isopentinyl pyrophosphate (eyaqalwa ukubamba iqhaza kwe-enzyme pyrophosphomevalonate decarboxylase).

Ekuhlelekeni kwe-squalene, isomerization sokuqala se-isopentenyl pyrophosphate kuya ku-dimethylallyl pyrophosphate kwenzeka (ngaphansi kwethonya le-isopentyl phosphatisomerase), bese isopentenyl pyrophosphate defence nge-dimethylallyl pyrophosphate (isibopho sobuchwepheshe senziwa phakathi kwe-C.₅ okokuqala no-C₅ into yesibili) ngokwakhiwa kwe-geranyl pyrophosphate (kanye ne-cleavage ye-molecule ye-pyrophosphate).

Esinyathelweni esilandelayo, isibopho phakathi kukaC₅ isopentenyl pyrophosphate ne-C₁₀ i-geranyl pyrophosphate - njengomphumela wokuncibilikisa owokuqala nowesibili, kwakhiwa i-farnesyl pyrophosphate bese kuthi kuqhamuke i-mocule elandelayo ye-pyrophosphate.₁₅.

Lesi sigaba siphela ngokubuyiselwa kwama-molekyuli amabili e-farnesyl pyrophosphate ku-C C₁₅- C₁₅ (ekhanda-kuya-ekhanda) ngokususwa kwama-molecule ama-2 e-pyrophosphate ngasikhathi sinye. Ukubuyiselwa kwama-molecule womabili, izifunda zamaqembu e-pyrophosphate asetshenziswa, elinye lawo liqedwa ngokushesha, okuholela ekwakhiweni kwe-pquophosphate exquale. Lapho i-NADPH incishisiwe (ngokususwa kwe-pyrophosphate yesibili), le nto ephakathi nendawo (ngaphansi kwethonya le-squalene synthase) iphenduka ibe yi-skavalen.

Kukhona imisebenzi emi-2 ekwakhiweni kwe-lanosterol: eyokuqala iphela ngokwakhiwa kwe-squalene epoxide (ngaphansi kwethonya le-squalene epoxidase), okwesibili - ngokujikeleza kwe-squalene epoxide kumkhiqizo wokugcina wesigaba - i-lanosterol. Ukuhambisa iqembu le-methyl kusuka ku-C₁₄ ku-C₁₃, futhi kusuka ku-C₈ ku-C₁₄ uyazi i-oxidosqualene-lanosterol cyclase.

Isigaba sokugcina sokuhlanganiswa sihlanganisa ukulandelana kwemisebenzi emi-5. Njengomphumela we-oxidation ye-C₁₄ Iqembu le-methyl le-lanosterol likhiqiza ikhemikhali ebizwa nge-14-desmethylanosterol. Ngemuva kokususwa kwamanye amaqembu amabili e-methyl (ku-C₄) into iba yi-zymosterol, futhi ngenxa yokudluliswa kwezibopho ezimbili₈= C₉ ukubeka uC₈= C₇ ukwakheka kwe-δ-7,24-cholestadienol kwenzeka (ngaphansi kwesenzo se-isomerase).

Ngemuva kokuhambisa isibopho esikabili C₇= C₈ ukubeka uC₅= C₆ (ngokwakhiwa kwe-desmosterol) kanye nokubuyiselwa kwezibopho eziphindwe kabili emaketeni aseceleni, kwakhiwa into yokugcina - cholesterol (noma kunalokho, cholesterol). I-enzyme engu- "δ" 24-reductase "iyalela" isigaba sokugcina se-cholesterol synthesis.

Yini ethinta uhlobo lwe-cholesterol?

Njengoba kunikezwe i-solubility ephansi ye-lipoproteins ephansi yamaseli (LDL), ukuthambekela kwabo kokuthola amakristalu we-cholesterol (ngokwakhiwa kwamathafa we-atherosulinosis emithanjeni yemithambo okwandisa amathuba okuba nezinkinga zenhliziyo nemithambo yegazi), ama-lipoprotein alesi sigaba ngokuvamile abizwa ngokuthi "i-cholesterol embi", ngenkathi i-lipoprotein ephezulu ene isisindo samangqamuzana (i-HDL) enezakhiwo ezihlukile (ngaphandle kwengozi ye-atherogenicity) ibizwa ngokuthi i-cholesterol "ewusizo."

Ngokubheka ukuhlobana kwalesi siphakamiso (umzimba awukwazi ukuba yilutho olungenamibandela noma oluyingozi yodwa), noma kunjalo, izindlela ezihlongozwayo okwamanje kubantu abanokuphakama okuphezulu kwe-vasology pathology ukulawula nokunciphisa i-LDL emazingeni aphezulu.

Ngokwesilinganiso esingaphezu kwe-4.138 mmol / l, ukukhethwa kokudla kunconyelwa ukunciphisa izinga labo laya ku-3.362 (noma ngaphansi), izinga elingaphezulu kuka-4.914 lisebenza njengesibonakaliso sokunquma ukwelashwa ukunciphisa ukwehlisa kwabo izidakamizwa.

Ukwanda kwengxenyana yegazi "cholesterol embi" kubangelwa yizici:

• ukusebenza komzimba ophansi (ukungasebenzi ngokomzimba);
• ukudla ngokweqile (ukuncika kokudla), kanye nemiphumela yako - isisindo ngokweqile noma ukukhuluphala;
• ukungalingani kokudla - ngokubhekelwa phambili kwamafutha we-trans, ama-carbohydrate agaya ukudla kalula (amaswidi, ama-muffin) kokulimaza okuqukethwe kwe-pectin, i-fiber, amavithamini, izinto zokulandela, ama-acid anamafutha okwakhiwa kwe-polyunsaturated;
• ukuba khona kokudakwa okujwayelekile kwabasendlini (ukubhema, ukuphuza utshwala ngendlela yeziphuzo ezahlukahlukene, ukusetshenziswa kabi kwezidakamizwa).

Ukuba khona kwe-pathology engalapheki kunomphumela onamandla ngokulinganayo:

• isifo se-gallstone;
• ukuphazamiseka kwe-endocrine nge-hyperproduction yama-hormone e-adrenal cortex, ukusweleka kwama-thyroid noma ama-hormone ocansi, noma isifo sikashukela mellitus;
• ukungasebenzi kahle kwe-renal ne-hepatic nokuphazamiseka kwezigaba ezithile zokuqanjwa kwama-lipoprotein "awusizo" avela kulezi zitho;
• ifa le-dyslipoproteinemia.

Isimo se-cholesterol metabolism ngqo sincike kwisimo se-microflora yamathumbu, esikhuthaza (noma esivimbele) ukumuncwa kwamafutha okudla, futhi futhi sibambe iqhaza ekwakhiweni, ekuguqulweni, noma ekubhujisweni kwama-sterols emvelaphi ye-exo native noma ye-endo native.

Futhi okuphambene nalokho, ukunciphisa inkomba yokuhola "okubi" cholesterol:

• imfundo yomzimba, imidlalo, ukudansa;
• ukugcina impilo enempilo ngaphandle kokubhema notshwala;
• ukudla okulungile ngaphandle kwe-carbohydrate elula yokugaya, enokuqukethwe okuphansi kwamafutha ezilwane zento efakwayo - kepha kunokuqukethwe okwanele kwe-fiber, i-polyunsaturated fatty acids, izinto ze-lipotropic (lecithin, methionine, choline), ukulandelela izinto, amavithamini.

Ividiyo evela kusazi:

Inqubo isemzimbeni kanjani?

Cishe ama-20% we-cholesterol angena emzimbeni ngokudla okudliwayo - akhiqiza ama-80% asele yedwa, ngaphezu kwesibindi, inqubo yokuqamba yenziwa yi-reticulum ebushelelezi ye-endoplasmic yamaseli:

• amathumbu;
• izindlala ze-adrenal;
• izinso
• izindlala zangasese.

Ngokungezelela emgomweni weklasikhi wokudala i-cholesterol molecule echazwe ngenhla, kuyenzeka futhi ukuyakha usebenzisa indlela engeyona eyemvelo. Ngakho-ke, enye yezinketho ukwakhiwa kwento ephuma glucose (okwenzeka kwamanye ama-enzyme nangaphansi kwezinye izimo zesitho somzimba).