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
5
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]
6
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)
7
Key Mechanisms
• Kinases: Transfer PO32- to substrate
• Phosphoglucose Isomerase
• Aldolase
• GAP Dehydrogenase
• Phosphoglycerate Mutase
8
Example of Kinase Activity
Step 1: Hexokinase
9
Phosphoglucose Isomerase
Reaction Mechanism
Step 2
10
PGI Reaction Mechanism
Base
Catalysis
11
PGI Reaction Mechanism
Acid
Catalysis
12
PGI Reaction Mechanism
Base catalyzes ring closure
H+
13
Glyceraldehyde 3-Phosphate
Dehydrogenase
Step 6
Remember:
Glycolysis produces 2
molecules of GAP, and
therefore 2 molecules
of NADH
14
GAP Dehydrogenase Mechanism
Free Enzyme
15
GAP Dehydrogenase Mechanism
Thiol
Addition
16
GAP Dehydrogenase Mechanism
Dehydrogenation
17
GAP Dehydrogenase Mechanism
Phosphate
Binding
Pi
18
GAP Dehydrogenase Mechanism
19
Phosphoglycerate Mutase
20
Phosphoglycerate Mutase
Mechanism
21
Pyruvate Kinase
22
What happens to pyruvate?
23
PRS
• What is the maximum number of
O2 molecules that hemoglobin
can bind?
1. One
2. Two
3. Three
4. Four
24
PRS
•
1.
2.
3.
4.
B cells mature in the ________.
Thymus
Bone marrow
Muscle tissue
Myosin
25
PRS
• Oxygen binding to myoglobin
results in what shaped curve?
1. Sigmoidal
2. Hyperbolic
3. Linear
4. Sinusoidal
26
PRS
• Which of the following amino
acids is not in the catalytic triad
of serine proteases?
1. Ser
2. Thr
3. His
4. Asp
27
PRS
•
1.
2.
3.
4.
What is Km?
The catalytic efficiency
The catalytic rate constant
1/2 Vmax
[S] at 1/2 Vmax
28