Fates of pyruvate Flashcards
What co-factor is necessary for glycolysis?
NAD+ for G3P to 1,3BPG
What fate of pyruvate produces NAD+?
Pyruvate to lactate
What is the enzyme used for the conversion of pyruvate to lactate?
Lactate dehydrogenase
Does the muscle prefer aerobic or anaerobic conditions?
Aerobic. LDH-5 (M4) has a high Km (low affinity) for pyruvate but as pyruvate levels increase during exercise, the Km is reached and lactate formation begins
How is ethanol formed?
By microbes. Pyruvatepyruvate decarboxylase to Acetaldehydealcohol dehydrogenase to Ehtanol
What bonds are microbes breaking during fermentation?
B1,4 glycosidic bonds
What cell processes ethanol?
Hepatocytes (liver). The rate limiting enzyme is alcohol dehydrogenase (Km 5mg/dl)
Why is it impossible to run while drunk?
The liver uses all the NAD+ to process the alcohol, none left for glycolysis = no ATP
What system engages when ADH is overloaded?
Microsomal enzyme oxidizing system
Why do drugs and alcohol not mix?
The MEOS is responsible for clearing drugs from the system. Together, all systems are overloading resulting in longer clearing time
Ethanol metabolism produces high levels of NADH. What is the result of this?
Shifts metabolism towards fatty acid synthesis
What causes the alcohol beer belly?
Alcohol intake reduces the amount of fat that your body burns as energy
What is the metabolism of Ethylene glycol? (Antifreeze)
Elthylene glycol alcohol dehydrogenase -> Glycoahldehyde -> Oxylate, Glycolate and Glyoxylate -> stops oxidative phosphorylation and TCA cycle
What is the remedy to ethylene glycol poisoning?
Introduce alcohol to try to stimulate alcohol metabolism
What organ does the TCA cycle take place?
Liver
What organelle does TCA take place?
Mitochondria
What is the rate limiting step of TCA?
Acetyl CoA to Citrate (Citrate synthase)
How does TCA inhibit glycolysis?
Citrate diffuses in to cytoplasm and inhibits PFK1
1st oxidation step of TCA?
Isocitrate -> a-KG, release NADH and CO2
What steps produce NADH?
Isocitrate -> a-KG, a-KG to succinyl Coa, malate to ooa
What steps produce CO2?
citrate -> isocitrate, isocitrate -> a-KG, a-KG -> succinyl CoA
What steps does Arsenic inhibit?
Pyruvate dehydrogenase (pyruvate -> AcCoA), a-KG dehydrogenase (a-KG to SuccCoA)
Stops respiration
What step produces a FADH2?
Succinate to FUmarate
What is the coupled reaction in the TCA?
Malate to Oxaloacetate. Malate product is favored but since OOA and NADH are constantly removed, drives system towards making OOA
What are TCA leaks?
Citrate (FA), OAA (Glucose) for other pathways
What is the committed step for TCA?
Isocitrate to a-KG
What must be reoxidized to continue cycle?
FAD (fumarate to malate)
