SURVEY OF BIOCHEMISTRY
Protein Function
1
PRS
In a protein, the most conformationally
restricted amino acid is_____ and the
least conformationally restricted amino
acid is ________.
1.
2.
3.
4.
Trp, Gly
Met, Cys
Pro, Gly
Ile, Ala
2
PRS
In a protein, the most conformationally
restricted amino acid is_____ and the
least conformationally restricted amino
acid is ________.
1.
2.
3.
4.
Trp, Gly
Met, Cys
Pro, Gly
Ile, Ala
3
PRS
The arrangement of the regular
structural elements and the positions of
atoms in the protein are considered
part of the ______.
1.
2.
3.
4.
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
4
PRS
The arrangement of the regular
structural elements and the positions of
atoms in the protein are considered
part of the ______.
1.
2.
3.
4.
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
5
PRS
Lysine can form a salt bridge by
associating with a nearby ____ residue.
1.
2.
3.
4.
Pro
Ser
Gln
Glu
6
PRS
Lysine can form a salt bridge by
associating with a nearby ____ residue.
1.
2.
3.
4.
Pro
Ser
Gln
Glu
7
PRS
Noncovalent forces that stabilize protein
structure include all of the following
except _______.
1.
2.
3.
4.
The hydrophobic effect
Salt bridges
Disulfide bridges
Metal-ion coordination
8
PRS
Noncovalent forces that stabilize protein
structure include all of the following
except _______.
1.
2.
3.
4.
The hydrophobic effect
Salt bridges
Disulfide bridges
Metal-ion coordination
9
PRS
Which of the following DNA sequences is
(are) palindromic?
1.
2.
3.
4.
AGCT
AAGNCTT
AGGA
#1 and #2
10
PRS
Which of the following DNA sequences is
(are) palindromic?
1.
2.
3.
4.
AGCT
AAGNCTT
AGGA
#1 and #2
5’-AGCT-3’
3’-TCGA-5’
5’-AAGNCTT-3’
3’-TTCNGAA-5’
5’-AGGA-3’
3’-TCCT-5’
11
Protein Function: Overview
• Transport
• Contraction
• Protection
• Catalysis
• Regulation
Chapter 7 - with emphasis on
Myoglobin and Hemoglobin
– Gene regulation
– Hormonal regulation
• Structural Support
12
Why focus on Mb and Hb?
Biological
Importance
13
Why focus on Mb and Hb?
14
Why focus on Mb and Hb?
• Biological Importance
• Role in Transport of O2
– Myoglobin: O2 transport to muscles
– Hemoglobin: O2 transport from lungs
• Ligand Binding
– Simple binding
– Cooperativity and Allosteric Interactions
15
Ligand Binding: General Concepts
• How can ligand binding be:
– Described?
– Measured?
– Regulated?
• Distinctions between binding
categories
– One Protein + One Ligand
– One Protein + Multiple Ligands
16
Heme is what O2 binds
Heme is a porphyrin prosthetic molecule
17
Myoglobin and Hemoglobin
Mb
- O2
Hb
- O2
Myoglobin
Hemoglobin
1
4
# subunits
18% identical
1
4
# heme groups
residues
8
8
# Alpha Helices
18
Structure Changes on Binding
Fig 6-38 shows Mb
“breathing”
How is O2 binding to Mb
described?
Show on board…
19
O2 Binding to Myoglobin
Shape indicates
simple binding of
O2 to Mb
20
Hb has 2 conformations
Without O2
T State
With O2
R State
21
O2 Binding to Hemoglobin
Arteries carry
oxygenated blood
Veins carry
deoxygenated
blood
22
Upcoming…
• More on Hb and Mb on Friday
• General concepts
– Muscle Contraction
– Antibodies
• Exam #1 on Thursday
– Boggs B6A 4-5 pm
23