Bio 10 - Energy Metabolism Flashcards
Which type of pyruvate is used to feed into the TCA cycle?
The pyruvate that has been converted to Acetyl-CoA.
What are the co-factors need to make pyruvate to Acetyl-CoA?
[TLC For Nobody] Thiamine pyrophosphate (TPP; the active form of thiamine). Lipoic acid. Coenzyme A (vitamin B5). FAD (vitamin B2). NAD+ (vitamin B3).
Which poison can inhibit Lipoic acid?
Arsenic; causes garlic breath, vomiting, rice-water stools.
What are the causes of PDH deficiency?
X-linked congenital defect. Acquired defect (arsenic exposure). Deficient in one of the B vitamins (especially B1; thiamine).
What does Citrate synthase do?
It converts Acetyl-CoA into citrate in the TCA (Krebs) cycle.
What is the rate-limiting enzyme in TCA cycle? What does it do?
It is Isocitrate dehydrogenase. It converts Isocitrate into alpha-ketoglutarate.
What does alpha-ketoglutarate dehydrogenase do?
Converts alpha-ketoglutarate into succinyl-CoA. It requires all the same co-factors as pyruvate dehydrogenase (TPP, Lipoic Acid, Coenzyme A, FAD, NAD+).
Where does TCA take place?
In the inner mitochondrial membrane.
What is Complex I in the mitochondria?
It is NADH reductase. It converts NADH to NAD+, while pumping a H+ ion into the intermembrane space. It also generates an electron that goes into Complex II.
Which substances inhibit Complex I?
Amytal. Rotenone. MPP.
Which substances inhibit Complex III?
Antimycin A.
Which substances inhibit Complex IV?
Cianide. Sodium Azide. Carbon monoxide. Hydrogen Sulfide.
Which substances inhibit ATPase?
Oligomycin A.
What is an uncoupling agent?
Uncouples the electron transport chain from the ATPase: it increases the permeability of the inner mitochondrial membrane to hydrogen ions, generating more heat in the body.
What are three uncoupling agents?
Thermogenin. Aspirin. 2,4-DNP.
Why are alanine and glutamine found in such high concentrations in the blood?
They are the two major carriers of nitrogen from tissue.
What is generally involved in transamination? What enzyme catalyses this reaction?
Transfer of the amino group of an amino acid to alpha-ketoglutarate to form glutamate. The remaining deaminated amino acid is a ketoacid (such as pyruvate) that is used in energy metabolism. Aminotransferase catalyzes the reaction.
How are aminotransferases named?
By donor of the amino group (alanine aminotransferase converts alanine to pyruvate and forms glutamate).
In addition to substrates, what is required by all aminotransferases?
Pyridoxal phosphate (a derivative of vitamin B6).
What are the two most important amintransferase enzymes? What reactions do they catalyze?
Alanine aminotransferase (ALT): converts alanine + alpha-ketoglutarate into glutamate + pyruvate. Aspartate Aminotransferase (AST): converts Glutamate + Oxaloacetate into alpha-ketoglutarate + Aspartate.
What are the two main transporters of nitrogen in the blood?
Alanine. Glutamine.
What are the major regulatory enzymes of the citric acid (TCA) cycle?
Citrate synthase. Isocitrate dehydrogenase. Alpha-ketoglutarate dehydrogenase.
What are the four things that can be done to pyruvate?
Converted to Oxaloacetate (using pyruvate carboxylase), Acetyl-CoA (using pyruvate dehydrogenase), Lactate (Lactate dehydrogenase), or Alanine (using ALT).
