Important Enzymes Flashcards
What is the function of hexokinase?
Conversion of glucose to glucose 6 phosphate in stage 1 of glycolysis or in glycogenesis tissues
Glucose + ATP –> glucose 6 phosphate + ADP
What is the function of glucokinase?
Conversion of glucose to glucose 6 phosphate in stage 1 of glycolysis or glycogenesis in liver
Glucose + ATP –> glucose 6 phosphate + ADP
What is the function of phosphofructokinase 1?
Conversion of fructose 6 phosphate to fructose 1,6 bisphosphate in step 3 of glycolysis
Fructose 6 phosphate + ATP –> fructose 1,6 bisphosphate + ADP
What is the function of pyruvate kinase?
Conversion of phosphoenol pyruvate to pyruvate in stage 10 of glycolysis
What is the function of lactate dehydrogenase?
Reduction of pyruvate to lactate in anaerobic respiration (stage 11 glycolysis)
What enzymes are deficient in galactosaemia?
Galactokinase
Galactose 1 phosphate uridyl transferase
Which enzyme reduced galactose to galacitol?
Aldose reductase
Where is glucose 6 phosphate dehydrogenase used?
In the pentose phosphate pathway
Conversion of G6P and NADP+ to C5 sugar and NADPH
What is the function of pyruvate dehydrogenase?
Converts pyruvate to acetyl~CoA to enter the TCA cycle
Irreversible
Where is isocitrate dehydrogenase used?
It is involved in the irreversible step in the TCA cycle ie production of CO2
What is the function of phosphoglucomutase?
In glycogenesis and glycogenolysis
Glucose 6 phosphate glucose 1 phosphate
Which enzymes are involved in adding UDP glucose to the glycogen molecule?
Glycogen synthase forms a 1,4 glycosidic bonds
Branching enzyme forms a 1,6 glycosidic bonds
Which enzymes are involved in removing glucose 1 phosphate from the glycogen molecule?
Glycogen phosphorylase breaks a 1,4 glycosidic bonds
Debranching enzyme breaks a 1,6 glycosidic bonds
What is the function of glucose 6 phosphatase and where is it found?
It converts glucose 6 phosphate to glucose in the liver for use as a fuel in all tissues in both glycogenolysis and gluconeogenesis
Glucose 6 phosphate + h2o –> glucose + Pi
What is the function of glycerol kinase?
Conversion of glycerol to glycerol phosphate for use in TAG synthesis or glycolysis
Glycerol + ATP –> Glycerol phosphate
What is the function of fatty acyl CoA synthase?
Activation of fatty acids in TAG metabolism
Joins CoA enzyme to S atom in fatty acid
Require ATP
What is the function of HMG reductase?
Conversion of HMG~CoA to cholesterol in ketone body synthesis pathway
What is the function of HMG lyase?
Conversion of HMG~CoA to ketone bodies (acetoacetate)
What is the function of HMG synthase?
Addition of CoA to HMG to give HMG~CoA for ketone body synthesis.
What is the function of fructose 1,6 bisphosphatase?
In gluconeogeneis, it bypasses the irreversible step 3 of glycolysis.
Fructose 1,6 bP + H2O –> fructose 6 phosphate + Pi
What is the function of PEPCK?
In gluconeogeneis it is used to bypass the irreversible step 10 of glycolysis
Converts oxaloacetate to phosphoenol pyruvate using GTP
What is the function of pyruvate carboxylase?
In gluconeogeneis it is used to bypass the irreversible step 10 of glycolysis
It converts pyruvate to oxaloacetate
What is the function of fatty acid synthase?
Multi enzyme complex used in fatty acid synthesis to build up a fatty acid from C2 sequentially
What is the function of acetyl~CoA carboxylase?
Used to produce malonyl~CoA from acetyl~CoA for fatty acid synthesis
Acetyl~CoA + CO2 + ATP –> malonyl~CoA + ADP + Pi
What is the function of aminotransferases? Give 2 examples.
Used in transamination to convert an amino acid to a keto acid ie transferring the NH2 group
Alanine amino transferase (alanine –> glutamate)
Aspartate amino transferase ( glutamate –> aspartate)
What is the function of L and D amino acid oxidises? Give 2 examples.
To convert amino acids to keto acids and ammonia
Glutaminase (glutamine –> glutamate)
Glutamate dehydrogenase (glutamate –> a ketoglutarate)
What causes phenylketonuria?
A defect in phenylalanine hydroxylase which oxidises phenylalanine to tyrosine
What causes homocystinuria?
Deficiency in cystathionine B synthase which converts homocysteine to cystathionine to cysteine
What is the function of lipoprotein lipase?
Responsible for removing TAGs from lipoproteins
What is the function of lecithin cholesterol acyltransferase?
LCAT converts a surface lipid to a core lipid in a lipoprotein in order to restore stability.
