Glycolysis and Glycogen Flashcards
Hexokinase
- Phosphorylates Glu to give G-6-P
- Traps the glucose in the cell because there are no G-6-P transporters
Glucokinase
- Less aggressive hexokinase
- Transforms Glu to G-6-P
- Affinity 500 fold weaker than Hexokinase
Phosphoglucose isomerase (PGI)
- Isomerizes an aldose to a ketose
- G6P to F6P
Phosphofructokinase (PFK)
- Transfers phosphoryl group
- F6P to F-1,6-BP
- Key in regulation of glycolysis
Aldolase
-Cleaves FBP into two trioses: DHAP and GAP
Triose P Isomerase
-Interconverts a ketose (DHAP) to an aldose (GAP) through an Enediol intermediate
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
-Oxidizes and phosphorylates GAP to 1,3-BPG
Phosphoglycerate kinase (PGK)
- Converts 1,3-BPG to 3PG
- Yields 2 ATP
- Substrate level phosphorylation
Phosphoglycerate mutase
- Moves the phosphoryl of 3PG to give 2PG
- Phosphohistidyl intermediate involved
Enolase
- Dehydration
- Coverts 2PG to PEP
Pyruvate kinase
- Coverts PEP to Pyruvate
- Produces ATP
- Substrate level phosphorylation
Lactate dehydrogenase
- Converts pyruvate to lactate using NADH
- Reversible
Conversion of Fructose into an glycolytic intermediate
- Hexokinase: converts Fructose to F6P
- In liver: Fructose converted to 2GAP using Fructokinase, F1P aldolase, glyceraldehyde kinase, and triose P isomerase
F1P Aldolase Deficiency
- Liver damage and hypoglycemia
- F1P accumulates and gluconeogenesis decreases
Conversion of Mannose to a gylcolytic intermediate
-Coverted to F6P using hexokinase and phosphomannose isomerase
Conversion of Galactose to a glycolytic intermediate
-Converted to G6P using galactokinase, UMP transferase, epimerase, and phosphoglucomutase
Galactokinase deficiency
- Galacitol formation
- Causes cataracts
- Solution: eliminate lactose from the diet
- Galactocemia
UMP transferase deficiency
- Causes mental retardation and liver failure
- Solution: eliminate lactose from diet
- Galactocemia
UDP-glucose pyrophosphorylase
-Converts G1P to UDP glucose in the synthesis of glycogen
Glycogen synthase
-Converts UDP to glycogen along with branching enzyme
Glycogen phosphorylase
-Breaks glycogen down to G1P along with a debranching enzyme
Phosphoglucomutase
-Interconverts G1P to G6P
Von Gierke Disease (Type 1 glycogen storage disease)
- Defective Glucose-6-phosphatase or transport system
- Affects liver and kidney
- Increased amount of glycogen with normal structure
- Massive enlargement of the liver, failure to thrive, severe hypoglycemia, ketosis, hyperuricemia, and hyperlipidemia
McArdle Disease (Type 5 glycogen storage disease)
- Defective phosphorylase
- Affects the muscle
- Moderately increased amount of glycogen
- Limited ability to perform strenuous exercise because of painful muscle cramps
Anderson Disease (Type 4 glycogen storage disease)
- Defecctive branching enzyme
- Affects the liver and spleen
- Normal amount of glycogen but with very long branches
- Progressive cirrhosis of the liver. Liver failure causes death before the age of 2.
