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35 Cards in this Set

  • Front
  • Back
What is a kinase?
kinase are enzymes that transfer phosphoryl groups from ATP to other compounds or from phosphorylated compounds to ATP
What is adenylate kinase?
is present in all tissues where it functions to maintain equilibrium concentrations of the three nucleotides AMP, ADP, and ATP
What is the driving force for the rxn of citrate synthase?
hydrolysis of citryl-CoA
Is citrate symmetrical?
yes; however the double bond is ALWAYS formed in the same position- this means 4 potential isomers can form but only 1 does
Does aconitase contain an Fe-S cluster?
yes; its an arrangment of 4 atoms of each (4Fe and 4S)
What does aconitase do?
it catalyzes the reversible isomerization of citrate and isocitrate; it removes water from citrate's lower arm: such that the product molecule has the R configuration
What intermediate is formed when aconitase catalyzes it rxn?
What do Fe-S clusters normally participate in?
redox processes (aconitase is an intriguing expection, its a dehydration-rehydration rxn)
Is isocitrate dehydrogenase NAD+ dependent?
What does the isocitrate dehydrogenase rxn produce?
CO2 and NADH; this the 1st time these products are produced
Why does isocitrate dehydrogenase (NAD dependent) require Mn2+ or Mg2+ as a cofactor?
it helps polarize the newly formed carbonyl group (polarizes the C=O bond)
What does a-ketoglutarate dehydrogenase produce?
the 2nd CO2 and NADH of the citric acid cycle
What is the a-ketoglutarate dehydrogenase rxn very similar to?
the pyruvate dehydrogenase rxn b/c they are both multi-enzyme complexes
What are the enzymes found in the a-ketoglutarate dehydrogenase mulit-enzyme complex?
E1= a-ketoglutarate dehydrogenase
E2= dihydrolipoyl transacetylase
E3= dihydrolipoyl dehydrogenase
How many rxns are catalyzed by pyruvate dehydrogenase complex?
5 rxns
Is succinyl-CoA a high energy thioester?
What is another name for succinyl-CoA synthetase?
succinate thiokinase
What substrate does succinyl-CoA synthetase use?
Mammals: GDP
Plants and Bacteria: ADP
What does nucleoside diphosphate kinase do?
it catalyzes the interconversion of ATP and GTP
What is the difference b/t synthetase and sythase?
synthetase is
Which enzyme in CAC is the only one to have substrate-level phosphorylation?
succinyl-CoA synthetase
(this reation occurs close to =)
What is substrate level phosphorylation?
the direct transfer of a phosphoryl group to ADP to generate ATP
After succinyl-CoA does its dirty work what major actions have occurred in CAC?
-one acetyl equivalent has been completely oxidized to 2 CO2
-2 NADH and 1 GTP have been generated

(now in order to complete the cycle, succinate must be converted back to oxaloacetate)
In the succinyl-CoA synthetase reaction what is the "high-energy mixed anhydride"?
In the succinyl-CoA synthetase reaction what is the "high energy intermediate"?
What is a "high energy" intermediate?
a currency that stores the energy given up in exergonic breakdown and allow endergonic processes to be driven
What are the four enzymes oxidation steps CAC?
isocitrate dehydrogenase
succinate dehydrogenase
alpha-ketoglutarate dehydrogenase
malate dehydrogenase
What is the only enzyme that is membrane bound and produces FADH2 from its FAD bound prothetic group?
succinate dehydrogenase- contains an FAD prothetic goup that is covalently linked to the enzyme via a His residue
What dirty work does FAD like to participate in?
oxidize alkanes such as succinate to alkenes such as fumarate
What dirty work does NAD+ like to participate in?
exergonic oxidation of alcohols to aldehydes or ketones
When does the reoxidation of FADH2 occur?
when electons are passed to the mitochondrial electron transport chain
What is special about the reaction that fumarate catalyzes?
stereospecific and probably has the OH addition before the H+ addition
What is the hydride ion transfer to NAD+ (catalyzed by malate dehydrogenase) very similar to?
lactate dehydrogenase and alcohol dehydrogenase
Is the reaction that malate dehydrogenase catalyzes endergonic or exergonic?
What pulls the reaction that malate dehydrogenase catalyzes?
citrate synthase reaction