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SURVEY OF BIOCHEMISTRY

Protein Function

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PRS

In a protein, the most conformationally restricted amino acid is_____ and the least conformationally restricted amino acid is ________.

1. Trp, Gly2. Met, Cys3. Pro, Gly4. Ile, Ala

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PRS

In a protein, the most conformationally restricted amino acid is_____ and the least conformationally restricted amino acid is ________.

1. Trp, Gly2. Met, Cys3. Pro, Gly4. Ile, Ala

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PRS

The arrangement of the regular structural elements and the positions of atoms in the protein are considered part of the ______.

1. Primary structure2. Secondary structure3. Tertiary structure4. Quaternary structure

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PRS

The arrangement of the regular structural elements and the positions of atoms in the protein are considered part of the ______.

1. Primary structure2. Secondary structure3. Tertiary structure4. Quaternary structure

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PRS

Lysine can form a salt bridge by associating with a nearby ____ residue. 1. Pro2. Ser3. Gln4. Glu

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PRS

Lysine can form a salt bridge by associating with a nearby ____ residue. 1. Pro2. Ser3. Gln4. Glu

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PRS

Noncovalent forces that stabilize protein structure include all of the following except _______.

1. The hydrophobic effect2. Salt bridges3. Disulfide bridges4. Metal-ion coordination

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PRS

Noncovalent forces that stabilize protein structure include all of the following except _______.

1. The hydrophobic effect2. Salt bridges3. Disulfide bridges4. Metal-ion coordination

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PRS

Which of the following DNA sequences is (are) palindromic?

1. AGCT2. AAGNCTT3. AGGA4. #1 and #2

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PRS

Which of the following DNA sequences is (are) palindromic?

1. AGCT2. AAGNCTT3. AGGA4. #1 and #2

5’-AGCT-3’3’-TCGA-5’

5’-AAGNCTT-3’3’-TTCNGAA-5’

5’-AGGA-3’3’-TCCT-5’

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Protein Function: Overview

• Transport• Contraction• Protection• Catalysis • Regulation

– Gene regulation– Hormonal regulation

• Structural Support

Chapter 7 - with emphasis onMyoglobin and Hemoglobin

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Why focus on Mb and Hb?

BiologicalImportance

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Why focus on Mb and Hb?

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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

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Ligand Binding: General Concepts

• How can ligand binding be:– Described?– Measured?– Regulated?

• Distinctions between binding categories– One Protein + One Ligand– One Protein + Multiple Ligands

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Heme is what O2 binds

Heme is a porphyrin prosthetic molecule

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Myoglobin and Hemoglobin

Myoglobin Hemoglobin 1 4 1 4 8 8

Mb- O2

Hb- O2

# subunits# heme groups# Alpha Helices

18% identical residues

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Structure Changes on Binding

Fig 6-38 shows Mb “breathing”

How is O2 binding to Mbdescribed?

Show on board…

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O2 Binding to Myoglobin

Shape indicatessimple binding of

O2 to Mb

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Hb has 2 conformations

Without O2

T StateWith O2 R State

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O2 Binding to Hemoglobin

Arteries carry oxygenated blood

Veins carry deoxygenated

blood

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Upcoming…

• More on Hb and Mb on Friday

• General concepts– Muscle Contraction– Antibodies

• Exam #1 on Thursday– Boggs B6A 4-5 pm