Upload
afnan-alkaff
View
240
Download
4
Tags:
Embed Size (px)
DESCRIPTION
nk,
Citation preview
GLUCONEOGENESISBiosynthesis of glucose 3 4 carbon noncarbohydrate precursorsEnzymes located in the cytosolGluconeogenic organsLiver Kidney cortexFates Catabolism by nervous tissue Utilization by skeletal muscles
GLUCONEOGENESISSUBSTRATES GLUCOGENIC AMINO ACIDSLACTATEGLYCEROLPROPIONATE
PRECURSORSGLUCOSEFructose 1,6 - bisphosphateDihydroxyacetone phosphateGlyceraldehyde 3 - phosphateGLYCEROLPYRUVATEGlycerol 3 - phosphatePhosphoenolpyruvateOxaloacetateALANINELACTATEOther amino acidsPROPIONATESUCCINYL-CoA
CORI CYCLESKELETAL MUSCLELIVERBLOODGLUCOSE2 PYRUVATE2 LACTATEGLUCOSE2 PYRUVATE2 LACTATE6 ATP2ATP
PYRUVATEOXALOACETATEPEPPYRUVATELACTATEOAA
GLUCOSE - ALANINE CYCLESKELETAL MUSCLELIVERBLOODGLUCOSE2 PYRUVATE2 ALANINEGLUCOSE2 PYRUVATE2 ALANINE6 ATP2ATP2NH22NH2UREA
2 OxaloacetateGlucose 6 - phosphateGLUCOSE2 PYRUVATEFructose 6 - phosphateFructose 1,6 - bisphosphatePhosphoenolpyruvateATPATPATPATP2GTP2ATP2ATP2NADH2NADH12H2OH2O3
BYPASS REACTIONS PYRUVATE to PHOSPHOENOLPYRUVATEPYRUVATE CARBOXYLASEGenerates OXALOACETATEMitochondrial matrixATP DependentBIOTIN dependentACETYL CoA positive allosteric activator
BYPASS REACTIONS PYRUVATE to PHOSPHOENOLPYRUVATE PHOSPHOENOLPYRUVATE CARBOXYKINASEDecarboxylation and phosphorylationCytosolReversibleGTP Dependent
PEP CARBOXYKINASECO2OXALOACETATEPHOSPHOENOLPYRUVATE
BYPASS REACTIONS FRUCTOSE 1,6 BISPHOSPHATE to FRUCTOSE 6 - PHOSPHATEFRUCTOSE 1,6 - BISPHOSPHATASELIVERKIDNEYSKELETAL MUSCLE
BYPASS REACTIONS GLUCOSE 6 PHOSPHATE to GLUCOSEGLUCOSE 6 - PHOSPHATASEIrreversibleHydrolysisEndoplasmic reticulum of the liverAbsent in the brain and skeletal muscleRequires Mg+
SUMMARY of REACTIONS
REACTANTSPRODUCTSPyruvate + CO2 + ATP +H2OOxaloacetate + ADP + PiOxaloacetate + GTPPhosphoenolpyruvate + GDPPhosphoenolpyruvate2 phosphoglycerate2 phosphoglycerate3 - phosphoglycerate3 phosphoglycerate + ATP1,3 bisphosphoglycerate1,3 bisphosphoglycerate + NADHGlyceraldehyde 3 PO4Glyceraldehyde 3 PO4Dihydroxyacetone PO4G3-P + DHAPFructose 1,6 bisphosphateFructose 1,6 bisphosphateFructose 6 phosphateFructose 6 phosphateGlucose 6 phosphateGlucose 6 phosphateGLUCOSE
a 14 glycosidic bonda (16)glycosidic bondGLYCOGEN
GLYCOGEN SYNTHESISGLYCOGENESISPhosphorylation of glucose Requires activated glucose UDP Glucose UDP Glu pyrophosphorylaseGLYCOGENIN 332 amino acids Self-glucosylating enzyme Glycogen primer
GLYCOGEN SYNTHASE ReactionOHOGLYCOGENINGLYCOGEN + 1O
GLYCOGEN SYNTHESIS UDP - GLUCOSE Glucose 1 - PO4GLUCOSE 6 PO4GLUCOSEATPADPUTPPPiGLYCOGEN(Glucose)n(Glucose)n +1HEXOKINASEUDP-Glc PYROPHOSPHORYLASEPHOSPHOGLUCOMUTASEGLYCOGEN SYNTHASE
BRANCH Formation a 1, 6 glycosidic bond Branching enzyme amylo 1,4 1,6 transglycosylase Transfers terminal residues 6 -7 residues
GLYCOGEN SYNTHESIS
GLYCOGEN DEGRADATIONGLYCOGENOLYSIS Phosphorolysis Requires inorganic phosphate a 1, 4 glycosidic bond Glucose 1 - phosphate
GLYCOGEN PHOSPHORYLASEHOGLYCOGENGLYCOGEN - 1HPO4
DEBRANCHING ENZYME
GLYCOGENOLYSISH2O
GLYCOGEN METABOLISMGlycogen breakdown requires the interplay of GLYCOGEN PHOSPHORYLASE, OLIGOTRANSFERASE, and a 1, 6 GLUCOSIDASEGlycogen is synthesized by a different pathway involving GLYCOGEN SYNTHASE and a BRANCHING ENZYME.SYNTHESIS and DEGRADATION are RECIPROCALLY REGULATED.
CARBOHYDRATES