Energy Metab.: PDH and Krebs Cycle Flashcards Preview

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Flashcards in Energy Metab.: PDH and Krebs Cycle Deck (20):
0

Modes of enzyme regulation

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Allosteric
Phosphorylation/Dephosphorylation
gene transcription

1

Fatty Acid energy pathway (Start with Triglycerides)
Result?

Triglycerides = 3 fatty acids + glycerol
Fatty acids + beta oxidation (in mitochondrium) = AcCoa

Results are AcCoa + 1 NADH + 1 FADH

2

Amino Acid energy pathway

AA = Pryuvate - PDH = AcCoa

3

Glucose energy pathway

Glucose or Glycerol - (glycolysis) - Pyruvate = AcCoA

4

PDH complex equation

Pyruvate + NAD+ + CoA ==> AcCoa + Co2 + NADH + H+

5

PDH a.k.a, fxn, location, reaction dynamics, composition

Pyruvate dehydrogenase complex
Covert pyruvate to AcCoa
Mitochondrial matrix
irreversible
3 enzymes, 5 coenzymes, 2 regulatory enzymes

6

PDH Regulation

Products of reaction competitively inhibit complex
active form = dephosphorylated
inactive form = phosphorylated
Kinase (that phosphorylates) activated by products and inhibited by reactants

7

PDH deficiency

Increased lactate, pyruvate and alanine
chronic lactic acidosis
severe neurological defects or death

8

TCA pathway

Acetyl Coa + Oxaloacetate => citrate => isocitrate => Alpha-ketogluterate => succnyl coa => succinate => fumerate => L-malate => oxaloacetate

9

energy producing TCA enzymes - which
located where

Isocitrate Dehydrogenase = NADH
Alpha-ketogluterate dehydrogenase = NADH
Succinyl CoA synthase = GTP
Succinate dehydrogenase = FADH2
Malate Dehydrogenase = NADH
location = mitochondrial matrix

10

TCA energy breakdown - one cycle

3 NADH + H, 1 FADH2 + 1GTP = 12 ATP (one cycle)

11

AcCoa Sources

Beta oxidation of fatty acids
PDH
Some Amino Acids

12

AcCoA paths

Oxidation - TCA
Liver - Ketone bodies
Cytosol - biosynthesis of sterols and long chains fatty acids

13

TCA regulation

Supply
PDH
Co-enzyme (FA and NAD+) availability
ADP + Pi availability

14

Fumarase Deficiency - result

severe neurological impairment, encephalomyopathy, and dystonia

15

TCA pathology

Fatal

16

Pyruvate dehydrogenase deficiency

congenital lactic acidosis

17

regulatory enzymes - inhibited by, [activated by]

citrate synthase - NADH and Succinyl CoA
isocitrate dehydrogenase - NADH and ATP, [ADP, Ca2+]
alpha-ketoglutarate dehydrogenase - ATP, GTP, NADH and Succinyl CoA, [Ca2+]

18

anabolic function of TCA

supply starting materials for biosynthetic processes

19

Anaplerotic reactions def., e.g.

Replenish intermediates of TCA
pyruvate carboxylase - turns pyruvate into oxoaloacetate
amino acids can also turn into 4 different intermediates, i.e. during fasting