Transcript SURVEY OF BIOCHEMISTRY - Georgia Institute of Technology

SURVEY OF BIOCHEMISTRY
Glycolysis
1
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
2
Introduction to Glycolysis
• Glycolysis:
breakdown of
sugars
• Primary start
point = glucose
• 10 enzymatic
reactions
3
Overview
Stage I of Glycolysis
• 2 ATP’s invested
• 1 Glucose is broken
into 2 phosphorylated
molecules
4
Overview
Stage II of Glycolysis
• 4 ATP’s recovered
• 2 NADH’s produced
• GAP is converted to
pyruvate
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Enzymes in Glycolysis
Stage 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 Glycolysis
Stage II: Energy Recovery
6.
Glyceraldehyde 3-Phosphate Dehydrogenase
•
7.
Uses NAD+ to form NADH
Phosphoglycerate Kinase [PGK]
•
Forms ATP (2 molecules)
8. Phosphoglycerate Mutase [PGM]
9.
Enolase
•
Forms high energy molecule
10. Pyruvate Kinase [PK]
•
Classify these
on board
Forms ATP (2 molecules)
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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 Isomerase
Reaction Mechanism
Step 2
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PGI Reaction Mechanism
Base
Catalysis
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PGI Reaction Mechanism
Acid
Catalysis
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PGI Reaction Mechanism
Base catalyzes ring closure
H+
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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
Phosphate
Binding
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. One
2. Two
3. Three
4. Four
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PRS
•
1.
2.
3.
4.
B cells mature in the ________.
Thymus
Bone marrow
Muscle tissue
Myosin
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PRS
• Oxygen binding to myoglobin
results in what shaped curve?
1. Sigmoidal
2. Hyperbolic
3. Linear
4. Sinusoidal
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PRS
• Which of the following amino
acids is not in the catalytic triad
of serine proteases?
1. Ser
2. Thr
3. His
4. Asp
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PRS
•
1.
2.
3.
4.
What is Km?
The catalytic efficiency
The catalytic rate constant
1/2 Vmax
[S] at 1/2 Vmax
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