Forensic Biology (Serology) FRSC 2001 Professor Bensley Alfred State College.
Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor...
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Transcript of Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor...
![Page 1: Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor Bensley.](https://reader035.fdocuments.us/reader035/viewer/2022081800/56649e555503460f94b4c072/html5/thumbnails/1.jpg)
Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins
CHEM 7784
Biochemistry
Professor Bensley
![Page 2: Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor Bensley.](https://reader035.fdocuments.us/reader035/viewer/2022081800/56649e555503460f94b4c072/html5/thumbnails/2.jpg)
CHAPTER 3.2 and 3.3 Peptides, Proteins, and Working with Proteins
• The structure and properties of peptides• The ionization behavior of and peptides • Various methods to characterize peptides and
proteins
Today’s Objectives: to understand
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Formation of Peptides •Peptides are small condensation products of amino acids
•They are “small” compared to proteins (Mw < 10 kDa)
![Page 4: Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor Bensley.](https://reader035.fdocuments.us/reader035/viewer/2022081800/56649e555503460f94b4c072/html5/thumbnails/4.jpg)
Peptide Ends are Not the Same•Numbering starts from the amino terminus
AA1 AA2 AA3 AA4 AA5
![Page 5: Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor Bensley.](https://reader035.fdocuments.us/reader035/viewer/2022081800/56649e555503460f94b4c072/html5/thumbnails/5.jpg)
The Three Letter Code
• Naming starts from the N-terminus
• Sequence is written as:
Ala-Glu-Gly-Lys
• Sometimes the one-letter code is used:
AEGK
![Page 6: Chapter 3.2 and 3.3: Peptides, Proteins, and Working with Proteins CHEM 7784 Biochemistry Professor Bensley.](https://reader035.fdocuments.us/reader035/viewer/2022081800/56649e555503460f94b4c072/html5/thumbnails/6.jpg)
Peptides: A Variety of Functions
• Hormones and pheromones
• Neuropeptides
• Antibiotics
• Protection, e.g. toxins
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Proteins are:
• Polypeptides (covalently linked
-amino acids) + possibly: • cofactors • coenzymes • prosthetic groups • other modifications
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Polypeptide Size in Some Proteins
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Classes of Conjugated Proteins
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What to Study about Peptides and Proteins?
•What is its sequence and composition?
•What is its three-dimensional structure?
•How does it find its native fold?
•How does it achieve its biochemical role?
•How is its function regulated?
•How does it interact with other macromolecules?
•How is it related to other proteins?
•Where is it localized within the cell?
•What are its physico-chemical properties?
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A Mixture of Proteins Can Be Separated
• Separation relies on differences in physico-chemical properties– Charge– Size– Affinity for a ligand– Solubility– Hydrophobicity– Thermal stability
• Chromatography is commonly used for preparative separation
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Column Chromatography
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Separation by Charge
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Separation by Size
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Separation by Affinity
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Electrophoresis for Protein Analysis
Separation in analytical scale is commonly done by electrophoresis
– Electric field pulls proteins according to their charge
– Gel matrix hinders mobility of proteins according to their size and shape
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SDS PAGE: Molecular Weight
• SDS – sodium dodecyl sulfate – a detergent
• SDS micelles bind to, and unfold, all the proteins– SDS gives all proteins an uniformly negative
charge– The native shape of proteins does not matter– Rate of movement will only depend on size: small
proteins will move faster
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