Ch18 - Pyruvate Preparation

Oxidation

2 Carbon fragment is oxidized and translated to Lipoamide to form Acetyllipoamide

What comes in/out of this reaction?

2 electrons go out

What makes up the pyruvate dehydrogenase complex (2 groups)

3 Enzymatic Activities 5 Co-enzymes

3 enzymes of pyruvate dehydrogenase complex

E1: pyruvate dehydrogenase E2: dihydrolipoyl transacetylase E3: dihydrolipoyl dehydrogenase

Which enzyme stimulates oxidative carboxylation of pyruvate

Enzyme 1: Pyruvage Dehydrogenase

Which enzyme in the pyruvate dehydrogenase complex is the primary site of regulation

Enzyme 1: Pyruvate Dehydrogenase Component

Catalytic Co-Enzyme of Enzyme 3

FAD

What happens when pyruvate from the cytosol is transported into the mitochondria?

It is converted to Acetyl CoA

Pyruvate is converted to what when the citric acid cycle is off?

Lactate

Catalytic Co-Enzyme of Enzyme 2

Lipoamide

Enzyme 2 uses what co-enzyme to keep everything together

Lipoamide arm

Oxidative Decarboxylation

Loss of carbon dioxide and loss of hydrogen to NADH

What two forms to the high transfer electrons take?

NADH and FADH2

Dihydrolipoamide Dehydrogenase

Re-oxidizes Dihydrolipomide so that it can be used in pyruvate conversion

Enzyme 3: Dihydrolipoyl Dehydrogenase

Regenerates lipoamide for continued reactions

Stochiometric Co-enzymes

Substrates that are regenerated after reaction

Catalytic Co-Enzyme of Enzyme 1

TPP

5 coenzymes of pyruvate dehydrogenase complex

TPP Lipoic Acid FAD CoA NAD+

3 Catalytic Coenzymes of the pyruvate dehydrogenase complex

TPP, Lipoic Acid, FAD

Step 1:

Decarboxylation of pyruvate by enzyme 1 (pyruvate dehydrogenase component)

2 Things that at high levels, stimulate E1

1. ADP 2. Pyruvate

3 Things that at high levels, down regulate E1

1. ATP 2. Acetyl CoA 3. NADH

2 Things that are necissary for Pyruvate to be converted to Acetyl CoA (which begins citric acid cycle)

1. ATP levels are low 2. Oxygen is available

2 Major parts of cellular respiration

1. Citric Acid Cycle 2. Oxidative Phosphorilization

3 Steps of conversion from pyruvate to Acetyl CoA

1. Decarboxylation 2. Oxidation 3. CoA Transfer

2 Fates of Pyruvate once it is converted to Acetyl CoA

1. Oxidation to CO2 2. Incorperation into fatty acids

2 Types of Co-enzymes in the pyruvage dehydrogenase complex

1. Stochiometric Enzymes 2. Catalytic Enzymes

3 Things that come out of the citric acid cycle

ATP, CO2, High transfer potential electrons

Why is the creation of Acetyl CoA not the committed step for the citric acid cycle?

Acetyl CoA can also be converted into fats

What happens to the acetyl charge in this step?

Acetyl charge goes from negative to positive

Transfer to Acetyl CoA

Acetyl group from acetyllipomide translated to Coenzyme A to make Acetyl CoA

Catalytic Co-enzymes

Attached to the enzyme

What comes in/out in this reaction?

CO2 goes out

2 Stochiometric Coenzymes of pyruvate dehydrogenase complex

CoA and NAD+

What comes in/out of this reaction?

CoA goes in

Step 3:

CoA transfer to acetyl group by enzyme 2 (Dihydrolipyl Transacetylace)

Cellular Respiration

Combustion of fuels into carbon dioxide and water, generating ATP

Pyruvate Dehydrogenase Complex

Decarboxylates pyruvate to form Acetyl CoA

3 Steps of pyruvate conversion to Acetyl CoA

Decarboxylation Oxidation Transfer to CoA

Pyruvate can be transported into the mitochondria is ATP levels are low to perform citric acid cycle What happens if ATP levels are high and where does the glucose go?

If ATP levels are high, glucose is sent to glycogen for storage

A high energy charge makes E1 Activated or Inactivated?

Inactivated

Phosphorylized Enzyme 1 is Activated or Inactivated?

Inactivated

Is pyruvate dehydrogenase on or off when the energy charge is high

Off

Step 2:

Oxidation of decarboxylated pyruvate by enzyme 1 (pyruvate dehydrogenase component)

Enzyme 1: Pyruvate Dehydrogenase

Oxidizes pyruvate and removes carbon to create NADH and CO2

What decides if pyruvate goes through the citric acid cycle?

Oxygen availability

Pyruvate Dehydrogenase (E1) is deactivated when it is __________

Phosphorylated

Method of E1 Regulation

Phosphorylization of E1 by a kinase

What is the primary enzyme responsible for the creation of Acetyl CoA in the mitochondria?

Pyruvage Dehydrogenase Complex

Phosphate deficiency causes lactic acid buildup because

Pyruvate Dehydrogenase is always off therefore lactic acid formation is the only way to generate ATP

Decarboxylation

Pyruvate attaches to TPP and Pyruvate Dehydrogenase catalizes decarboxylation

Where in the cell does glycolysis occur?

The cytoplasm

What reaction is the link between glycolysis and the citric acid cycle?

The irreversible conversion of pyruvate to Acetyl CoA

What enzyme component assists in keeping pyruvate in the pyruvate dehydrogenase complex?

The lipoamide arm

Where in the cell does the citric acid cycle occur?

The mitochondria

Beriberi

Thiamine defficiency that causes neurologic issues by inactivating TPP kinetic co-enzyme

Why does a lack of thiamine cause neurological deficits?

Thiamine is necissary for pyruvate conversion to acetyl CoA. The fuels made by this conversion into acetyl CoA are essential to the nervous system

Why does lactate generation occur?

To replenish NADH from glycolysis

Enzyme 2: Dihydrolipoyl Transacetylase

Transfers acetyl group to CoA