Metabolism Enzymes Flashcards
Rate-limiting enzyme of glycolysis?
phosphofructokinase-1 (PFK-1)
Rate-limiting enzyme of fermentation?
Lactate dehydrogenase
Rate-limiting enzyme of glycogenesis?
glycogen synthase
Rate-limiting enzyme of Glycogenolysis?
glycogen phosphorylase
Rate-limiting enzyme of Gluconeogenesis?
fructose-1,6-bisphosphatase
Rate-limiting enzyme of Pentose phosphate pathway?
glucose-6-phosphate dehydrogenase
What are the 3 irreversible enzymes of glycolysis and their counter enzyme in gluconeogenesis?
Hexokinase/glucokinase → glucose-6-phosphatase
Phosphofructokinase-1 (PFK-1) → fructose-1,6-phosphatase
Pyruvate kinase → pyruvate carboxylase + PEPCK
How does ATP effect the rate of glycolysis?
ATP inhibits PFK-1 (there is enough energy, so need to keep producing it), even though PFK-1 uses it for its phosphate group. This inhibition is allosteric, and ATP can bind at different sites on the enzyme either helping it (active site) or inhibiting it (allosteric site).
What enzyme hydrolyzes tryacylglycerol in adipocytes?
Hormone sensitive lipase (HSL)
What enzyme hydrolyzes tryacylglycerol in lipoproteins?
Lipoprotein lipase –> VLDLs
What is the carrier of free fatty acids in the blood?
Albumin
What is the carrier of tryacylglycerol and cholesterol in the blood?
Lipoproteins
From where to where do VLDL transport tryacylglycerol?
Liver to peripheral tissues
From where to where do LDL transport cholesterol?
Liver to peripheral tissues
From where to where do HDL transport cholesterol?
Peripheral tissues to kidneys
What is an IDL?
VLDL remnant
What is the “good kind” of cholesterol?
HDL because it carries excess cholesterol from blood vessels for excretion
What is the rate-limiting enzyme of cholesterol synthesis?
HMG-CoA reductase
What is the rate-limiting enzyme of fatty acid synthesis?
Acetyl-CoA carboxylase
What is the rate-limiting enzyme of fatty acid beta-oxidation?
Carnitine acyl-transferase I
What is the role of the LCAT enzyme?
Catalyzes the production of cholesteryl esters
What is the role of pyruvate kinase in glycolysis?
Catalyzes the final reaction, which produces 2 ATP per glucose molecule
