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Lecture 26
Pyruvate Dehydrogenase Complex
| Question | Answer |
|---|---|
| The conversion of Pyruvate to Acetyl-CoA is catalyzed by which enzyme? | Pyruvate Dehydrogenase Complex |
| List the substrates, co-factors, and products found in the reaction of Pyruvate to Acetyl-CoA. | Substrates(pyruvate, NAD+, and SH), Co-factors(TPP, Lipoate, and FAD), Products(Acetyl-CoA, CO2, and NADH) |
| List the different molecules acetyl-CoA can be broken down into. | Cholesterol, Fatty acids, and Ketone bodies |
| What vitamin is required for the oxidative decarboxylation of an alpha-keto-acid? | Vitamin B6 = PLP |
| What side group from an amino acid is replaced with a carboxyl group to form an alpha keto acid? | The NH3 group (primary amine) is replaced by a carboxyl group |
| What are the corresponding alpha-keto-acids for alanine, aspartate, and glutamate? | pyruvate, oxaloacetate, alpha-keto-glutarate |
| What does pyruvate dehydrogenase complex do to alpha-keto-acids? Is it reversible? | Oxidative decarboxylation. This process is irreversible. |
| The pyruvate dehydrogenase complex is made up of multiple copies of what three enzymes? | (E1)pyruvate dehydrogenase, (E2)dihydrolipoyl transacetelase, (E3)dihidrolipoyl dehydrogenase |
| What reaction does E1 catalyze? | Decarboxylation of pyruvate to produce hydroxyethyl-TPP followed by oxidation to form an acetyl group. |
| Describe the reaction that takes place in E1 | Pyruvate is decarboxylated and covalently binds to TPP. The resulting hydroxyethyl-TPP is oxidized to an acetyl group which then binds to the reduced lipotate of E2. |
| What reaction does E2 catalyze? | E2 reduces the cofactor (Lipoyl group) allowing the acetyl group to bind. CoA then binds the acetyl group and the product is released. |
| What type of covalent bond is formed between the lysine side chain and the lipoyl co-factor? | Amide bond |
| What reaction takes place in E3? | The lipoyl cofactor is oxidized by FAD+. The FADH2 that is subsequently produced is used to generate NADH + H. |
| Is lipoic acid a vitamin? | No |
| What functions in the body has lipoic acid been implicated in? | Improved memory, antioxidant properties |
| Thiamine is also known as vitamin ___? | B1 |
| Deficiencies in Thiamine (vitamin B1) cause these diseases. | BeriBeri and Wernicke-Korsakoff syndrome |
| What vitamin makes up part of CoA? | Pantothenic Acid = Vitamin B5 |
| What are the dietary sources of pantothenic acid? | Whole grain cereals, legumes, meat, and eggs |
| Which part of the molecule forms the bond between acetate and CoA to form Acetyl-CoA? | The reactive thiol (-SH) group forms thioester bond between acetate and CoA. |
| Lipoate and biotin are both examples of? | Biological tethers |
| What molecules positively regulate the pyruvate dehydrogenase complex? | ADP, NAD+, CoA and Ca2+ in muscles |
| What molecules negatively regulate the pyruvate dehydrogenase complex? | ATP, NADH, Acetyl-CoA |
| Why does the liver also positively regulate pyruvate dehydrogenase complex with insulin? | When insulin is present, the liver converts excess glucose into Acetyl-CoA to form fatty acids for storage. |
| Where is the pyruvate dehydrogenase complex found in eukaryotes and prokaryotes? | It is found in the mitochondria of eukaryotic cells and the cytosol of prokaryotic cells |
| How many ATPs can be generated from 1 NADH? | 2.5 |
Created by:
bettyboucher
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