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Glycogen. Glycogen. Liver ~ 4 % 72 g Muscle ~ 1 % 245 g Extracellular glucose 0,1 % 10 g Adult - man 70 kg His liver 1,8 kg His muscle mass 35 kg Blood volume 10 l. Glycogen. Muscle: Glucose substrate for muscle glycolysis Liver: Glucose store, Export of hexose Blood sugar

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Glycogen1
Glycogen

  • Liver

    • ~ 4 % 72 g

  • Muscle

    • ~ 1 % 245 g

  • Extracellular glucose

    • 0,1 % 10 g

      Adult - man 70 kg

      His liver 1,8 kg

      His muscle mass 35 kg

      Blood volume 10 l


Glycogen2
Glycogen

  • Muscle:

    • Glucose substrate for muscle glycolysis

  • Liver:

    • Glucose store,

    • Export of hexose

    • Blood sugar

  • Glycogenosis

    • Deff. Of enzymes

    • Muscle weakness ¢N



  • As a meal containing carbohydrates is eaten and digested,

  • blood glucose levels rise

  • pancreas secretes insulin.

  • Glucose from the portal vein enters the liver cells (hepatocytes).

  • Insulin acts on the hepatocytes to stimulate the action of several enzymes, including glycogen synthase.

  • Glucose molecules are added to the chains of glycogen as long as both insulin and glucose remain plentiful. In this postprandial or "fed" state, the liver takes in more glucose from the blood than it releases.

  • .


  • After a meal has been digested and glucose levels begin to fall, insulin secretion is reduced, and glycogen synthesis stops.

  • About four hours after glycogen begins to be broken down and converted again to glucose.



Glycogen synthesis
Glycogen synthesis

  • Muscle

    • Hexokinase

  • Liver

    • Glucokinase

  • Phosphoglucomutase

    • Glucose-1,6-P cofactor

  • Glycogen

    • Primer: glycogenin

      • 37 kDa glycosilated Tyr






Glycogen

P

P

P

Glygenolysis

Glycogenesis

Glucose-1-P


Effect of epinephrin
Effect of epinephrin

X

Stimulus

R

cAMP

40X

ATP

Cent. Nervous syst.

Inakt. Protein Kinase A

Aktive Protein Kinase A

10X

Adrenal cortex

Phosphorylase Kinaseb

Phosphorylase Kinase a

100X

Glykogen phosphorylaseb

Glykogen phosphorylasea

1000X

Epinephrin

X

Glykogen

Glukose 1 P

10000X


GDP

b

a

g

ATP

GTP

cAMP


4 cAMP

R

R

R

R

C

C

C

C



Tein, koffein

cAMP

AMP

PKA

PKA

Phosphorylase-kinase b

Phosphorylase-kinase a

Ca2+

Phosphorylase a

Phosphorylase b

AMP


Glycogen

P

P

P

Glycogenolysis

Glycogenesis

Glucose-1-P



Glycogen synthase
Glycogen synthase

  • Glycogen synthasea –dephosphorylated

  • Glycogen synthaseb –phosphorylated

    • 4 identical subunit

    • 7 Ser-OH residues/subunit


Glycogen synthase1
Glycogen synthase

  • 6 different protein kinases

    • Phophorylase kinase (Ca2+/Calmodulin dep)

    • Ca2+/Calmodulin dep.

    • GSK-3:

    • GSK-4

    • GSK-5

  • Glucose-6-P: allosteric activator of Glycogene-synthase kinaseb

  • Insulin/muscle:

    • dephosphorylation / activation of Glycogen-synthaseb


Von gierke s disease
Von Gierke’s Disease

Glucose 6-phosphatase: liver and kidney

Here is another liver with a pale, bulging surface. This time the liver is filled with glycogen in von Gierke's disease, the glycogen storage disease of children.

Severly enlarged liver, severe hypoglycemia, lactic acidosis, ketosis, hyperuricemia, hyperlipemia


Pompe s disease
POMPE'S DISEASE

When mannose 6-phosphate

tags are added to acid

maltase enzyme molecules,

the molecules stick to receptors

(docking sites) on the

muscle cells and are

carried deeper inside

the cells, where they're needed.

Without mannose 6-phosphate

tags, acid maltase

(1,4-D-Glucosidase)

enzyme molecules can't

enter muscle cells from

the bloodstream.

ENZYME TREATMENT BENEFITS BABIES WITH POMPE'S DISEASE

Babies with a metabolic muscle disorder known as Pompe's disease,

or acid maltase deficiency, usually don't survive infancy because they lack a vital enzyme that normally breaks down glycogen in the heart and skeletal muscle cells.

Cardiac failure in infancy; liver, heart, muscle


Forbe s disease type iii glycogenosis
Forbe’s disease, Type III glycogenosis

  • also called Cori's disease , or glycogenosis type III rare hereditary disease in which the the metabolic breakdown of glycogen to the simple sugar glucose is incomplete, allowing intermediate compounds to accumulate in the cells of the liver. Affected persons lack the enzyme amylo-1,6-glucosidase, one of several enzymes involved in glycogen breakdown. Children with the disease have enlarged livers (which usually…


Andersen s disease
Andersen’s disease

  • also called Glycogenosis Type Iv, extremely rare hereditary metabolic disorder produced by absence of the enzyme amylo-1:4,1:6-transglucosidase (branching enzyme), which is an essential mediator of the synthesis of glycogen. An abnormal form of glycogen, amylopectin, is produced and accumulates in body tissues, particularly in the liver and heart. Affected children appear normal at birth but fail to thrive and later lose…

    Liver cirrhosis, death usually before 24 months


Mcardle s disease
McArdle's Disease

Phosphorylase stain: Absent

Muscle fibers stain yellowMyophosphorylase deficiency: McArdle's disease

Phosphorylase stain: Normal

more darkly than type I