Term
Synthesis of Glycogen
G-6-P -> UDP glucose |
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Definition
G-6-P -> G-1-P by PGM
Phosphoglucomutase.
G-1-P + UTP -> PPi + UDP-glucose
UDP-glucose Pyrophosphorylase
Highly exergonic, Ensures progress to
UDP glucose.
(UTP gets cleaved to UMP which binds G-1-P) |
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Term
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Definition
Glycogenin: attaches initial gluucose at its tyrosine OH group(#194)
(autocatalytic, self-glucosylating)
Glycogen Synthase: creates a-1,4
linkages only to existing glycogen at
non reducing ends
Branches are created by Branching enzyme(glucosyl-a-1,6 transferase) |
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Term
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Definition
UDP + ATP -> UTP + ADP
Nucleoside diphosphate kinase
Intermembrane of mitochondria. |
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Term
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Definition
Glycogen Phosphorylase lyses a-1,4 bond using Phosphoric Acid as co-substrate
Breaks down to 4 glucose chain.
Limit dextrin is transfered to an existing branch by debranching enzyme.
The last glucose is hydrolyzed by a-1,6 glucosidase function of debranching enzyme.(free glucose) |
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Term
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Definition
Covalently boud pyridoxal phosphate as prosthetic group.
50% of PlP in phosphorylase |
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Term
| Allosteric Modulators of glycogen breakdown |
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Definition
Activators: Ca++, 5'AMP.
Inhibitors: Free glucose, g-6-P, aATP |
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Term
| Hormonal control of glycogen breakdown in muscle |
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Definition
Epinephrine:
PKA activation ->
active phosphatase kinase ->
Phosphorylase B -> A(active)
Attaching 2 Pi's to phosphorylase b will activate it(phosphorylase A)
Ca++ stimulates Phosphatase kinase and phosphorylase |
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Term
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Definition
PKA phosphorylates glycogen synthase at serine residues(Inhibits)
Glycogen Synthase active in desphophorylates state(a state)
Inactive in phosphorylated state(b) |
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Term
Glycogen Synthase Deficiency
(Type 0 glycogenosis) |
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Definition
Inability to form glycogen at normal rates.
Fasting hypoglycemia and ketosis
Unresponsive to glucagon.
Only liver Affected |
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Term
Branching Enzyme deficiency
(Andersens Type IV) |
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Definition
Liver and Muscle affected
Long straight chains just α-1,4 linkages
Hypotonia, retardation, atrophky. Cirrhosis and splenomegaly
Still born or death within first 3 years |
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Term
Muscle phosphorylase deficiency
(mcardles syndrome, type V) |
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Definition
Exercise intolerance, cramping
Muscle affected |
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Term
Debrancher Deficiency
(cori's disease, Type III) |
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Definition
Liver and muslce, sometimes only one
Hepatomegaly, mild hypoglycemia |
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Term
Acid a-glucosidase deficiency
(Pompe's disease, type II) |
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Definition
Any tissue that synthesizes glycogen and has lysosomes
Acidic α-glucosidase mutation(breaks 1,4 and 1,6). Glycogen builds up in lysosome
Cardiac/respiratory failure -> death within first 2 years of life.
Muscle hypertrophy, Normal glycogen metabolism, and energy metabolism |
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Term
Phosphofructokinase(PFK) deficiency
(Type VII Tarui's disease) |
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Definition
Skeletal muscle and RBC
In RBC -> PFK activity reduced by 50%
Hemolysis and hyperbilirubinemia
Glucose cannot relieve smptoms, little
lactate produced.
(RBC has no glycogen but name is convienent) |
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Term
| Pyruvate Dehydrogenase Steps |
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Definition
1. Carbon stripped from pyruvate
Release as CO2
2. Substrate activated with thiamin
pyrophosphate(TPP)
3. Acetate fitted with Coenzyme A-SH
4. NAD+ reduced to NADH -> Acetyl-CoA |
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Term
| Pyruvate Dehydrogenase Co-enzymes |
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Definition
H20 Soluble vitamins:
Thiamin pyrophosphate(TPP)
Flavin Adenine Finucleotide(FAD)
Nicotine Adenine Dinucleotide(NAAD)
Coenzyme ASH(Pantothenic Acid)
Lipoic Acid: Susceptible to arsenite poisining. 2 copies 4-SH groups. |
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Term
| Control of Pyruvate Dehydrogenase |
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Definition
Allosteric:
Activators: Pyruvate, AMP, NAD+, Ca+
Inhibitors: NADH, ATP, Acetyl-CoA
Acetyl-CoA becomes folic acid and cholesterol
Phosphorylation inactivates. |
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Term
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Definition
Thiamin(vitamin B-1) deficiency.
(co-enzyme of pyruvate dehydrogenase)
Aka lack of acetyl CoA production
Extreme weakness, paralysis, edema. |
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Term
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Definition
Reduction to Lactate Using NADH
Carboxylation to oxaloacetate
Direct transamination to alanine
Oxadative decarboxylation to form Acetyl-CoA |
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