Enzymes of glyolysis and gluconeogenesis Flashcards
What are the five types of enzymatic reactions in glycolysis?
Phosphorylation, phosphoryl shift, isomerisation, dehydration, redox
What types of enzymes phosphorylate?
Kinases
What types of enzymes shift phosphoyl?
Mutases (Pi remains within molecule but shifts from one O to another O)
What types of enzymes isomerise?
Isomerases
What general isomerisation reactions happen in glycolysis?
Aldose ketose
What types of enzymes dehydrate?
Dehydratases
What types of enzymes redox?
Dehydrogenases
What are the ten enzymes involved in glycolysis (in order of reactions)?
Hexokinase/glucokinase; phosphoglucoisomerase; phosphofructokinase; fructose disphosphate aldolase; triose phosphate isomerase; GALP dehydrogenase; phosphoglycerate kinase; phosphorylglycerate mutase; enolase; pyruvate kinase
What does hexokinase/glucokinase do?
Glucose –> glucose-6-p; requires Mg2+
What does phosphoglucoisomerase do?
Glucose-6-p –> fructose-6-p; carbonyl oxygen shifted from C1 to C2; aldose –> ketose
What does phosphofructokinase do?
Fructose-6-p –> fructose-1,6-bisp; requires Mg2+
What does fructose disphosphate aldolase do?
Fructose-1,6-bisp –> GALP + DHA-P; aldol cleavage
What does triose phosphate isomerase do?
DHA-P –> GALP; ketose –> aldose
What does glyceraldehyde-3-phosphate dehydrogenase do?
GALP –> glycerate-1,3-bisphosphate
What does phosphoglycerate kinase do?
ADP + Pi –> ATP
What does phosphorylglycerate mutase do?
Glycerate-3-phosphate –> glycerate-2-phosphate
What does enolase do?
Glycerate-2-phosphate –> phosphorenolpyruvate
What does pyruvate kinase do
ADP + Pi –> ATP
What is gluconeogenesis?
Formation of glucose from non-carb sources
What compounds may enable gluconeogenesis?
Lactate, glutamate, alanine
Where does gluconeogenesis occur?
Primarily in liver
What is the purpose of gluconeogenesis?
Maintain blood glucose concentration during fasting and starvation
How is lactate converted to glucose?
Lactate shuffled to liver. Lactate –> pyruvate; pyruvate –> oxaloacetate (pyruvate carboxylase); oxaloacetate –> phosphophenolpyruvate (phosphophenolpyruvate carboxylase); phosphophenolpyruvate –> F-1,6,BP; F-1,6-BP –> F-1-P (fructose-1,6-phosphatase); F-1P –> glucose
How is fructose-1,6-phosphatase regulated?
AMP inhibits action of fructose-1,6-phosphatase and stimulates phosphofructokinase (opposing enzyme); ATP stimulates action of fructose-1,6-phosphatase and inhibits phosphofructokinase (opposing enzyme)
What basic chemicals are needed for gluconeogenesis?
Oxygen and ATP
