Mannose thiab qabzib, txawm hais tias muaj tib lub qauv molecular (C ? H ?? O ?), yog ob qho tib si aldoses thiab C-2 isomers (piv txwv li cov kev taw qhia ntawm pawg hydroxyl ntawm cov pa roj carbon thib ob txawv), tab sis lawv txoj kev metabolic thiab lub cev muaj zog sib txawv. Cov hauv qab no muab cov ncauj lus kom ntxaws sib piv ntawm lawv cov metabolic sib txawv los ntawm ntau qhov kev xav:

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1. Txoj hnyuv nqus

Glucose:

Kev nqus tau zoo: Nws feem ntau yog thauj los ntawm SGLT1 (sodium glucose cotransporter 1) hauv cov kab mob hauv plab hnyuv me. Qhov nqus tau siab heev (> 95%), uas tuaj yeem nkag mus rau hauv cov hlab ntsha sai thiab nce ntshav qab zib.

Nyob ntawm sodium ion gradient. cov

Mannose:

Kev nqus tsis zoo: feem ntau yog los ntawm kev yooj yim diffusion (tejzaum nws cuam tshuam nrog GLUT tsev neeg thauj khoom xws li GLUT5 lossis cov channel zoo sib xws). Qhov nqus tau qis heev (kwv yees li 10-20%), thiab feem ntau ntawm cov mannose unabsorbed nkag mus rau hauv txoj hnyuv thiab yog fermented los ntawm plab hnyuv kab mob los yog tawm nrog quav.

2. Nkag mus rau hauv cov hlab ntsha

Glucose:

Tom qab nqus tau, nws ncaj qha nkag mus rau hauv cov hlab ntsha ntawm cov hlab ntsha, ua rau cov ntshav qab zib nce sai.

Mannose:

Qhov nqus tau qis, thiab qhov concentration ntawm mannose hauv cov ntshav yog qhov tsawg heev (qhov ceev ceev ntshav ntshav siab yog li 50 μmol / L, qis dua 4-6 mmol / L ntawm cov piam thaj). Kev tswj qhov ncauj ntawm mannose tsis ua rau muaj kev hloov pauv loj hauv cov ntshav qab zib.

3. Thawj kauj ruam ntawm cov ntaub so ntswg uptake thiab metabolism

Glucose:

Insulin-dependent: Cov leeg nqaij thiab cov nqaij adipose uptake ntawm qabzib yog nyob ntawm qhov taw qhia ntawm insulin (ntawm GLUT4 transporter).

Hexokinase / Glucokinase: Tom qab nkag mus rau hauv cov hlwb, nws yog phosphorylated los ntawm hexokinase (HK) (cov ntaub so ntswg hauv lub cev) lossis glucokinase (GK) (siab) rau qabzib-6-phosphate (G6P). Qhov no yog lub hauv paus hub molecule ntawm qab zib metabolism.

Mannose:

Tsis yog nyob ntawm insulin: cov ntaub so ntswg uptake tsis nyob ntawm insulin.

Mannokinase (MK): Nws yog feem ntau phosphorylated los ntawm mannokinase nyob rau hauv daim siab (nrog rau me me nyob rau hauv lwm cov ntaub so ntswg xws li ob lub raum) rau mannose-6-phosphate (Man-6-P). Qhov no yog tus nqi tseem ceeb txwv cov kauj ruam hauv mannose metabolism.

Phosphomannose isomerase (PMI): Txiv neej-6-P hloov mus rau fructose-6-phosphate (F6P) los ntawm phosphomannose isomerase. F6P yog ib qho khoom nruab nrab ntawm txoj kev glycolysis.

4. Cov txheej txheem metabolic tseem ceeb

Glucose:

Glycolysis zog mov: G6P tuaj yeem nkag mus rau glycolysis txoj hauv kev los tsim lub zog (ATP).

Glycogen synthesis: Lub synthesis thiab khaws cia glycogen hauv daim siab thiab cov leeg.

Txoj kev pentose phosphate: tsim NADPH thiab ribose-5-phosphate (siv los txo cov biosynthesis thiab nucleotide synthesis).

Fat synthesis: Thaum muaj ntau dhau, nws hloov mus ua rog.

Mannose:

Hloov mus rau hauv glycolytic intermediates: Tom qab PMI hloov mus rau F6P, nws tuaj yeem nkag mus rau hauv glycolytic txoj hauv kev (qhov kawg tuaj yeem hloov mus rau hauv qabzib lossis tag nrho oxidized rau lub zog mov).

Glycosylation precursor: Nws lub luag haujlwm tseem ceeb yog los ua cov pab pawg qab zib pib rau kev sib txuas N-txuas qab zib chains! Txiv neej-6-P tuaj yeem hloov mus ntxiv rau hauv GDP mannose hauv vivo, ua haujlwm ncaj qha ntawm mannose residues hauv glycoproteins thiab glycolipids.

Glycosylation: Mannose yog ib qho tseem ceeb ntawm cov tub ntxhais oligosaccharide saw hauv protein N-txuas glycosylation hloov kho (xws li txiv neej ? GlcNAc ?). Cov txheej txheem no tshwm sim hauv endoplasmic reticulum thiab Golgi apparatus, thiab tseem ceeb heev rau cov protein folding, stability, localization, thiab muaj nuj nqi (xws li cov tshuaj tiv thaiv, cov tshuaj hormones, thiab cell adhesion molecules).

Kev hloov pauv mus rau qabzib / glycogen: Kev ua tau zoo yog qis, thiab qee qhov F6P thim rov qab glycolysis txoj hauv kev tsim G6P, uas tom qab ntawd hloov mus rau cov piam thaj lossis glycogen, tab sis kev koom tes me me.

5. Kev cuam tshuam rau cov ntshav qabzib thiab insulin

Glucose:

Cov ntshav qab zib nce siab: yog qhov tseem ceeb ntawm cov ntshav qab zib.

Kev mob siab rau cov tshuaj insulin secretion: pancreatic beta hlwb ncaj qha pom qhov nce hauv cov ntshav qab zib thiab tso cov tshuaj insulin.

Mannose:

Yuav luag tsis cuam tshuam rau cov ntshav qab zib: absorbs tsawg dua, metabolizes tsis tsim cov piam thaj, thiab tsis cia siab rau insulin.

Tsis stimulating insulin secretion: tsis muaj cov ntshav qabzib stimulation signals.

6. Core sib txawv hauv physiological functions

Glucose:

Cov haujlwm tseem ceeb: Lub hauv paus tseem ceeb ntawm lub zog nrawm (tshwj xeeb yog lub hlwb, cov leeg, thiab cov qe ntshav liab), tswj cov ntshav qab zib homeostasis.

Mannose:

Lub luag haujlwm tseem ceeb: Cov khoom tseem ceeb ua ntej rau glycosylation biosynthesis, txhawb nqa cov qauv thiab kev ua haujlwm ntawm glycoproteins thiab glycolipids (kev lees paub ntawm tes, teeb liab hloov, kev tiv thaiv, protein folding, thiab lwm yam).

Kev ua haujlwm thib ob: Tiv thaiv kab mob urinary (los ntawm kev thaiv cov kab mob adhesion).

7. Clinical daim ntawv thov sib txawv

Glucose:

Kev siv zog ntxiv (infusion), kev kho mob hypoglycemic, kuaj ntshav qabzib siab.

Mannose:

Kev tiv thaiv kab mob urinary rov tshwm sim (tseem ceeb yog tsom rau Escherichia coli) thiab kho cov kab mob glycosylation tshwj xeeb tsawg (xws li CDG Ib MPI deficiency).