Metabolism 2 Flashcards
What is the difference between the H4 (heart) isozyme and M4 isoenzyme of LDH?
1) The H4 isozyme has a higher affinity for substrates than the M4 enzyme.
2) High levels of pyruvate inhibit the H4 isoenzyme but not the M4 isoenzyme.
3) The H4 isoenzyme works between in aerobic conditions, whist the M4 isoenzyme works better in anaerobic conditions.
An increase in what LDH isoenzyme is indicative on a heart attack?
An increase in serum levels of H4 is indicative of a heart attack as it released from damaged heart muscle cells.
What is an Apoenzyme and Haloenzyme?
Apoenzyme = inactive enzyme.
Haloeznyme = an active enzyme formed by the combination of an apoenzyme with a coenzyme.
What is an Oxidoreductase and name an example of one.
Oxidoreducatses catalyse redox reaction in which one substrate is reduced whilst another is oxidised.
Lactate dehydrogense is an example.
Name two flavoproteins that act as cofactors.
FMN and FAD (as they are very tightly bound to their enzymes).
What is the ‘Asian Flush Syndrome?’
It is the build up of acetaldehyde due to the lack of aldehyde dehydrogense.
What is main conserved motif in Alcohol dehydrogenase?
The Rossman Fold.
What are the two types of enzyme reactions?
Random, sequential, double-displacement mechanism (ping-pong reaction).
What type of mechanism does Lactate Dehydrogenase use?
The Ternary Complex Formation.
What is the E1 enzyme of the Pyruvate Dehydrogenase complex and what is its function?
It is Pyruvate dehydrogenase and function to decarboxylate pyruvate to form hydroxyethyl-TPP.
Give an example of a reaction that uses an oxidoreductase.
The conversion of pyruvate to L-lactate uses the oxidoreductase ‘lactate dehydrogenase’.
(Pyruvate is reduced whilst NADH is oxidised)
How are fatty acids digested to be used for energy?
1) They are degraded to form glycerol and fatty acid.
2a) The glycerol is transported to the liver and converted to either pyruvate or glucose.
2b) The fatty acids are transported to the energy-requiring tissues. There they undergo fatty acid oxidation to form acetyl-CoA and enter the citric acid cycle.
What is required for fatty acid oxidation to acetyl-CoA?
ATP, Coenzyme A and AcylCoA synthetase.
How many active sites does the enzyme Fatty Acid Synthase have?
Seven.
