GLUCONEOGENEZA - WordPress.com

GLUCONEOGENEZA - WordPress.com

GLUCONEOGENEZA GLUCONEOGENEZA Glicogenul hepatic acoper necesarul de G pt 10-18 ore n absena aportului de CH GNG este sinteza G din precursori neglucidici pe o cale metabolic special ce implic E mitocondriale i citosolice Are rol n meninerea glicemiei

90% din GNG are loc n Fi pe parcursul nopii (aport alimentar ntrerupt), 10% n Ri Dac sistarea aportului alimentar se prelungete: 40% din G va fi neosintetizat n Ri SUBSTRATURILE GNG

Molecule mici care prin prelucrare conduc la sinteza de G: intermediari ai glicolizei i ai c. Krebs Glicerolul, lactatul i - cetoacizii rezultai din dezaminarea AA glucogeni A. GLICEROLUL rezult din hidroliza TAG din esutul

adipos i este transportat pe cale sangvin la nivelul Fi fiind fosforilat n prezena glicerol-kinazei la glicerol-fosfat ce va fi oxidat la DHAP (intermediar glicolitic) Adipocitele nu pot fosforila glicerolul deoarece nu conin glicerol-kinaza SUBSTRATURILE GNG

SUBSTRATURILE GNG B. Lactatul eliberat n circulaie din muchiul striat n efort i de celulele lipsite de mitocondrii ( eritrocitele) SUBSTRATURILE GNG C. Aminoacizii rezultai prin hidroliza proteinelor sunt pp surs de G jeun - cetoacizii (OAA, - cetoglutaratul derivai din metabolizarea

AA glucogeni) ptrund n ciclul citric i formeaz OAA, precursor direct al PEP (decarboxilare) Acetil-CoA i precursorii acesteia (acetoacetatul, lizina i leucina) nu particip direct la sinteza G ( reacia catalizat de PDH este irev. ); genereaz corpi cetonici fiind compui cetogeni SUBSTRATURILE GNG

n sinteza G din lactat sau Py intervin 7 reacii glicolitice reversibile i 3 reacii reacii ireversibile ce tb scurtcircuitate prin 4 reacii favorabile energetic REACIILE SPECIFICE ALE GNG

A. Carboxilarea piruvatului n glicoliza: conversia irev. a PEP la Py n prezena PK n GNG: REACIILE SPECIFICE ALE GNG Py OAA

REACIILE SPECIFICE ALE GNG Piruvat-carboxilaza necesit legarea covalent a biotinei la gruparea - amino a unui rest de lizin formnd biocitina Intermediar R. are loc mitocondriile hepatice i renale; OAA= 1) S al

GNG sau 2) o surs ce poate compensa deficitul de intermediari ai c. Krebs; n miocite: OAA pt al 2-lea efect REACIILE SPECIFICE ALE GNG Reglarea alosteric Acetil-CoA activeaz piruvat-carboxilaza [Acetil-CoA ] intramitoc. determin sintezei de OAA ( jeun)

[Acetil-CoA ] piruvat-carboxilaza este inactiv, iar Py este oxidat n prezena PDH la acetil- CoA ce va fi oxidat n ciclul Krebs REACIILE SPECIFICE ALE GNG

OAA MALAT MALAT OAA- Oxaloacetat

OAA nu traverseaz direct MMI fiind redus la malat (MDH mitoc)ce va fi transportat din mitocondrii n citosol unde va fi reoxidat (MDH citosol.) REACIILE SPECIFICE ALE GNG PEPCK

Cuplarea celor 2 reacii este favorabil energetic pt PEP REACIILE SPECIFICE ALE GNG Defosforilarea Fr-1,6-difosfatului n prezena Fr-1,6difosfatazei scurtcircuiteaz reacia irev. a FFrK-1 cu formare de Fr-6-fosfat; reacie reglatorie important a GNG [AMPc] atest scderea rezervelor energetice i inhib Fr1,6-difosfataza [AMPc], [ATP] stimuleaz GNG [Fr-2,6-difosfat] i rezervele energetice reduse inhib Fr-1,6difosfataza

[Fr-2,6-difosfat] i rezervele energetice crescute stimuleaz Fr-1,6-difosfataza REACIILE SPECIFICE ALE GNG REACIILE SPECIFICE ALE GNG Defosforilarea G-6-fosfatului n prezena G-6-fosfatazei unteaz reacia ireversibil a hexokinazei fiind favorabil

energetic sintezei de G liber (Fi i Ri). REACIILE SPECIFICE ALE GNG REGLAREA GNG Depinde de : [glucagon] plasm ; [substraturi gluconeogenetice] GLUCAGONUL stimuleaz GNG prin 3 mecanisme: 1. Reduce [Fr-2,6-difosfat] cu activarea Fr-1,6-difosfatazei ;

inhibarea FFrK 2. Inducerea sintezei E: Glucagonul + transcripia genei pt PEPCK Insulina - transcripia genei pt PEPCK REGLAREA GNG

3. Modificarea covalent a activitii enzimatice [AMPc] + proteinkinaza AMPcdependent cu + PK inactive fosforilate rata de conversie a PEP la Py, cu orientarea spre GNG

REGLAREA GNG Disponibilitatea S AA glucogeni

Activarea alosterica a piruvat-kinazei hepatice exercitata de Acetil-CoA jeun (prin lipoliza cu -oxidarea AG in exces) cu orientarea spre GNG Inhibitia alosterica exercitata de AMP a Fr-1,6-difosfataza AMP + FFrK [AMP] + caile metabolice care oxideaza substantele nutritive in vederea obtinerii de energie

ATP si NADH rezultate din catabolism sunt necesare in GNG; -oxidarea AG: acetil-CoA ce + piruvat-carboxilaza GLICOLIZA

GLUCONEOGEEZA

Recently Viewed Presentations

  • Scale Factor & Scale Drawings Understanding Scales All

    Scale Factor & Scale Drawings Understanding Scales All

    A scale is the ratio between two sets of measurements. Scales can use the same units or different units. The photograph shows a scale drawing of the model train. A . scale drawing. is a proportional drawing of an object....
  • till - Woods Hole Oceanographic Institution

    till - Woods Hole Oceanographic Institution

    In 2006, turned over <40m tCO2e, growth expected Emerging and thus still being defined OIF does not currently access any regulatory markets Ownership of carbon credits for Kyoto parties only The ocean isn't part of the territory of a Kyoto...
  • Risk Management and Financial Institutions

    Risk Management and Financial Institutions

    * VaR and Regulatory Capital Regulators base the capital they require banks to keep on VaR The market-risk capital is k times the 10-day 99% VaR where k is at least 3.0 Under Basel II, capital for credit risk and...
  • Title slide with an image

    Title slide with an image

    Monash Postgraduate Association (MPA) Monash Research Graduate School (MRGS) Health, Wellbeing and Development. Library. MRGS exPERT series. General (eg. time management, relating to your supervisor) Information Technology. Statistics. Introduction to Intellectual Property.
  • Pericarditis Dr. Jamal Dabbas Interventional cardiologist & internist

    Pericarditis Dr. Jamal Dabbas Interventional cardiologist & internist

    Pericardial effusion is initially asymptomatic, but cardiac tamponade has a distinct clinical presentation, including hypotension, tachycardia, jugular venous congestion, and pulsus paradoxus. Echocardiography is the most important diagnostic procedure and usually reveals an anechoic pericardial space.
  • Encouraging Encouraging

    Encouraging Encouraging

    Evangelism Ministries USA/Canada Region. ... one of the sociological characteristics of a holiness church is an unwritten goal of avoiding disagreement. You remember that verse: "Follow peace with all men, and holiness, without which no man shall see the Lord"...
  • Chapter 6 Section 2 Canada - Weebly

    Chapter 6 Section 2 Canada - Weebly

    Natives originally settled in Canada when they crossed the land bridge from Asia to North America thousands of years ago. The people of Canada today originally immigrated there for many reasons. Most trace their roots back to English and French...
  • Coherent Time-Varying Graph Drawing with Multifocus+Context Interaction Kun-Chuan

    Coherent Time-Varying Graph Drawing with Multifocus+Context Interaction Kun-Chuan

    Thank you National Science Council, Taiwan NSC-99-2221-E-006-066-MY3 NSC-100-2628-E-006-031-MY3 NSC-100-2221-E-006-188-MY3 U.S. National Science Foundation IIS-1017935 [email protected] Motivation Dynamic or time-varying graph drawing Spatiotemporal coherence Focus+context (F+C) visualization Stable F+C viewing Aesthetic quality Dynamic stability ...