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Chapter 3 Proteins and Polypeptides George Plopper.

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1 Chapter 3 Proteins and Polypeptides George Plopper

2 Figure 03.13A: The light and heavy chains interact to form binding sites at the tips of the short arms of the antibody.

3 Antibody facts worth knowing Like all proteins, antibodies can be denatured by SDS and other harsh detergents Antibodies are proteins secreted by immune cells called B cells. Antibodies can be isolated from serum (blood) (polyclonal), or from a single B cell colony (monoclonal). Every different antibody has a unique Fab region. All antibodies isolated from the same species of animal have nearly identical Fc regions.

4 Figure 03.13B: Each domain in the heavy and light chains is tinted a different color for easier identification. Protein Data Bank ID: 1IGY. Harris, L. J., Skaletsky, E., and McPherson, A., J. Mol. Biol. 275 (1998): 861-872.

5 Figure 03.14: Five classes of bonds that stabilize protein structure.

6 Figure 03.15: Seven different types of molecules can be covalently attached to amino acid side chains.

7 Figure 03.16: Many proteins have more than one binding site. Allosteric binding sites help control the shape and function of a protein.

8 Figure 03.17: Occupancy of an allosteric GTP binding site controls a G protein subunit's shape. Three different conformations of the subunit are overlaid for comparison. Photo courtesy of Heidi E. Hamm and Will Oldham, Vanderbilt University Medical Center.

9 Figure 03.18: Proteasomes digest proteins in the cytosol.

10 Figure 03.19: Most membrane proteins and engulfed proteins are digested by lysosomes.

11 Figure 03.20: Extracellular proteins are digested by proteinases.

12 Methods in Cell & Molecular Biology Cell fractionation – Detergents – Centrifugation – Gel electrophoresis Protein isolation and detection – Immunoprecipitation – Western blotting

13 Detergents - Amphiphiles Triton-X-100 Sodium Dodecyl Sulfate (SDS, aka Sodium Lauryl Sufate) IONIC = DENATURING NONIONIC = NOT DENATURING

14 Centrifugation http://www.coleparmer.com/TechLibraryArticle/30

15 Gel electrophoresis SDS Polyacrylamide Gel Electrophoresis (SDS PAGE) SDS Polyacrylamide Gel Electrophoresis (SDS PAGE) Western blotting

16 Sample Western Blot

17 Sources http://biomoleculaire.blogspot.com/ http://employees.csbsju.edu/hjakubowski/cla sses/ch331/Techniques/TechElectrophoresis.h tm http://employees.csbsju.edu/hjakubowski/cla sses/ch331/Techniques/TechElectrophoresis.h tm http://www.labome.com/review/gene/mouse /Irs1-antibody-western-blot.html http://www.labome.com/review/gene/mouse /Irs1-antibody-western-blot.html


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