Term
| Phosphofructokinase -1 (PFK-1) |
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Definition
catalyzes the phosphorylation of fructose-6-phosphate to fructose 1,6-bisphosphate. PFK-1 is the key enzyme that sets the pace of glycolysis, the rate-limiting step of the pathway.
PFK-1 is inhibited allosterically by ATP and citrate, but conversely activated by AMP. Super-regulator for PFK-1 is 2,6-bisphosphate, the most potent activator which overrides the ATP inhibition.
PFK-1 is a sensor for the energy charge state of the cell.
PFK-1 is also inhibited by high [H+], which is generated from the production of pyruvate and lactate. This inhibition stops the continuous production of lactate and consequent acidosis. |
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Term
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Definition
| Phosphorylation of glucose during glyoclysis. In liver mainly glucokinase. |
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Term
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Definition
Citrate regulation ensures that the cell will have a preference for fatty acids being utilized as fuel which is energetically more favorable.
Citrate increases the F-1,6 bisphosphatase activity which counteracts the inhibition by F-2,6 bisphosphate. The result is favorable for gluconeognesis. |
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Term
| Fructose 2,6-bisphosphate |
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Definition
PFK-1 is activated by fructose 2,6-bisphosphate, the most potent activator which overrides the ATP inhibition.
not an intermediate in metabolism but a super regulator in control of glycolysis and gluconeogensis to ensure their reciprocal control.
High concentration of [F-2,6-BP] activates glycolysis by stimulating PFK-1 activity. At the same time high [F2.6-BP] inhibits the activity of fructose-1,6 bisphosphatase, a reversible step in gluconeogensis |
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Term
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Definition
Catalyzes conversion of F-6P->F-2,6-BP
Has kinase domain to synthesize F-2,6-BP and a phosphatase domain to hydrolyze F-2,6-BP.
PFK-2 activity regulated by protein kinase A. When phosphorylated, PFK2 phosphatase activity active and when dephosphorylated, the kinase activity is turned on. |
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Term
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Definition
activates protein kinase A which in turn inhibits
the production of F 2,6-BP by phosphorylation of the kinase domain of PFK-2.
Protein kinase A will phosphorylate and activate many other metabolic enzymes. |
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Term
| dihydroxyacetone phosphate |
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Definition
| DHAP is converted to glycerol 3-phosphate which is needed for triacylglycerol synthesis. |
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Term
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Definition
F-2,6-BP is inhibited by phosphorylation of PK2 by protein kinase A.
Glycerol is converted to glyceraldehyde-3-phosphate by glycerol kinase and glycolysis pathway can be pushed backwards to create glucose. |
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Definition
| Can be converted to 2,3-BPG which binds Hb and facilitates oxygen release. |
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Term
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Definition
| substrate level phosphorylation by conversion of 1,3-BPG->3-PG |
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Term
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Definition
Substrate level phosphorylation during conversion of phosphoenolpyruvate ->pyruvate
Pyruvate kinase is tightly regulated since it controls the the outflow of the glycolytic pathway. The activity is regulated via protein phosphorylation by cAMP protein kinase A activated by glucagon. It plays a role in cancer cell metabolism which favors glycolysis and anaerobic lactate production for energy. |
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Term
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Definition
| activates phosphoprotein phosphatase activities that dephosphorylate enzymes, which in turn causes activation of glycolysis. |
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Term
| Products formed from pyruvate following glycolysis |
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Definition
acetaldehyde->ethanol (yeast)
lactate
acetyl coA
Alanine
Oxaloacetate |
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Term
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Definition
converts pyruvate to lactase while replenishing supply of NAD+
Humans have two different types of LDH subunits, the M type and the H type, which form five tetrameric isomers. The LDH isozymes concentration in plasma is a diagnostic tool for tissue damages. |
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Definition
| catalyzes pyruvate-> alanine |
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Definition
| catalyzes pyruvate->oxaloacetate |
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Term
| Galactose-1-phosphate uridyl transferase |
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Definition
| converts Gal-1-P to UDP-galactose which is converted to UDP-glucose which enters glycolysis as G-1-P |
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Term
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Definition
fructose-1-P -> glyceraldehyde/dihydroxyacetone P
Enables fructose to enter at stage 2 of glycolysis |
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