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SURVEY OF BIOCHEMISTRY

Glycolysis

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Announcements

• Exam #2 on June 26– Chapters 7, 8, 11, 12, 14

• Bring calculators

• Study Session with Vonda – Thursday, June 26; 2-3:45 pm– Boggs 228

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Introduction to Glycolysis

• Glycolysis: breakdown of sugars

• Primary start point = glucose

• 10 enzymatic reactions

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Overview

Stage I of Glycolysis

• 2 ATP’s invested

• 1 Glucose is brokeninto 2 phosphorylated molecules

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Overview

Stage II of Glycolysis

• 4 ATP’s recovered

• 2 NADH’s produced

• GAP is converted to pyruvate

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Enzymes in GlycolysisStage I: Energy Investment

1. Hexokinase• Uses ATP

2. Phosphoglucose Isomerase [PGI]

3. Phosphofructokinase [PFK]• Uses ATP

4. Aldolase• Splits 6C into two 3C molecules

5. Triose Phosphate Isomerase [TIM]

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Enzymes in GlycolysisStage II: Energy Recovery

6. Glyceraldehyde 3-Phosphate Dehydrogenase• Uses NAD+ to form NADH

7. Phosphoglycerate Kinase [PGK]• Forms ATP (2 molecules)

8. Phosphoglycerate Mutase [PGM]

9. Enolase• Forms high energy molecule

10. Pyruvate Kinase [PK]• Forms ATP (2 molecules)

Classify theseon board

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Key Mechanisms

• Kinases: Transfer PO32- to substrate

• Phosphoglucose Isomerase

• Aldolase

• GAP Dehydrogenase

• Phosphoglycerate Mutase

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Example of Kinase Activity

Step 1: Hexokinase

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Phosphoglucose IsomeraseReaction Mechanism

Step 2

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PGI Reaction Mechanism

BaseCatalysis

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PGI Reaction Mechanism

AcidCatalysis

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PGI Reaction Mechanism

H+

Base catalyzes ring closure

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Glyceraldehyde 3-Phosphate Dehydrogenase

Step 6

Remember:Glycolysis produces 2 molecules of GAP, and therefore 2 molecules of NADH

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GAP Dehydrogenase Mechanism

Free Enzyme

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GAP Dehydrogenase Mechanism

Thiol Addition

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GAP Dehydrogenase Mechanism

Dehydrogenation

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GAP Dehydrogenase Mechanism

PhosphateBinding

Pi

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GAP Dehydrogenase Mechanism

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Phosphoglycerate Mutase

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Phosphoglycerate Mutase Mechanism

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Pyruvate Kinase

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What happens to pyruvate?

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PRS

• What is the maximum number of O2 molecules that hemoglobin can bind?

1. One2. Two3. Three4. Four

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PRS

• B cells mature in the ________.1. Thymus2. Bone marrow3. Muscle tissue4. Myosin

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PRS

• Oxygen binding to myoglobin results in what shaped curve?

1. Sigmoidal2. Hyperbolic3. Linear4. Sinusoidal

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PRS

• Which of the following amino acids is not in the catalytic triad of serine proteases?

1. Ser2. Thr3. His4. Asp

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PRS

• What is Km?

1. The catalytic efficiency2. The catalytic rate constant3. 1/2 Vmax

4. [S] at 1/2 Vmax