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35 Cards in this Set
- Front
- Back
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What is a kinase?
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kinase are enzymes that transfer phosphoryl groups from ATP to other compounds or from phosphorylated compounds to ATP
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What is adenylate kinase?
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is present in all tissues where it functions to maintain equilibrium concentrations of the three nucleotides AMP, ADP, and ATP
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What is the driving force for the rxn of citrate synthase?
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hydrolysis of citryl-CoA
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Is citrate symmetrical?
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yes; however the double bond is ALWAYS formed in the same position- this means 4 potential isomers can form but only 1 does
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Does aconitase contain an Fe-S cluster?
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yes; its an arrangment of 4 atoms of each (4Fe and 4S)
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What does aconitase do?
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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
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What intermediate is formed when aconitase catalyzes it rxn?
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cis-aconitate
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What do Fe-S clusters normally participate in?
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redox processes (aconitase is an intriguing expection, its a dehydration-rehydration rxn)
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Is isocitrate dehydrogenase NAD+ dependent?
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yes
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What does the isocitrate dehydrogenase rxn produce?
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CO2 and NADH; this the 1st time these products are produced
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Why does isocitrate dehydrogenase (NAD dependent) require Mn2+ or Mg2+ as a cofactor?
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it helps polarize the newly formed carbonyl group (polarizes the C=O bond)
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What does a-ketoglutarate dehydrogenase produce?
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the 2nd CO2 and NADH of the citric acid cycle
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What is the a-ketoglutarate dehydrogenase rxn very similar to?
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the pyruvate dehydrogenase rxn b/c they are both multi-enzyme complexes
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What are the enzymes found in the a-ketoglutarate dehydrogenase mulit-enzyme complex?
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E1= a-ketoglutarate dehydrogenase
E2= dihydrolipoyl transacetylase E3= dihydrolipoyl dehydrogenase |
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How many rxns are catalyzed by pyruvate dehydrogenase complex?
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5 rxns
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Is succinyl-CoA a high energy thioester?
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yes
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What is another name for succinyl-CoA synthetase?
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succinate thiokinase
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What substrate does succinyl-CoA synthetase use?
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Mammals: GDP
Plants and Bacteria: ADP |
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What does nucleoside diphosphate kinase do?
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it catalyzes the interconversion of ATP and GTP
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What is the difference b/t synthetase and sythase?
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synthetase is
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Which enzyme in CAC is the only one to have substrate-level phosphorylation?
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succinyl-CoA synthetase
(this reation occurs close to =) |
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What is substrate level phosphorylation?
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the direct transfer of a phosphoryl group to ADP to generate ATP
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After succinyl-CoA does its dirty work what major actions have occurred in CAC?
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-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) |
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In the succinyl-CoA synthetase reaction what is the "high-energy mixed anhydride"?
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succinyl-phosphate
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In the succinyl-CoA synthetase reaction what is the "high energy intermediate"?
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3-Phospho-His
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What is a "high energy" intermediate?
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a currency that stores the energy given up in exergonic breakdown and allow endergonic processes to be driven
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What are the four enzymes oxidation steps CAC?
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isocitrate dehydrogenase
succinate dehydrogenase alpha-ketoglutarate dehydrogenase malate dehydrogenase |
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What is the only enzyme that is membrane bound and produces FADH2 from its FAD bound prothetic group?
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succinate dehydrogenase- contains an FAD prothetic goup that is covalently linked to the enzyme via a His residue
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What dirty work does FAD like to participate in?
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oxidize alkanes such as succinate to alkenes such as fumarate
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What dirty work does NAD+ like to participate in?
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exergonic oxidation of alcohols to aldehydes or ketones
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When does the reoxidation of FADH2 occur?
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when electons are passed to the mitochondrial electron transport chain
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What is special about the reaction that fumarate catalyzes?
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stereospecific and probably has the OH addition before the H+ addition
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What is the hydride ion transfer to NAD+ (catalyzed by malate dehydrogenase) very similar to?
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lactate dehydrogenase and alcohol dehydrogenase
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Is the reaction that malate dehydrogenase catalyzes endergonic or exergonic?
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endergonic
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What pulls the reaction that malate dehydrogenase catalyzes?
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citrate synthase reaction
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