Reed We mon Data Analysis Problem by Marianna Paap to accompany The Cell: A ar h
ID: 80274 • Letter: R
Question
Reed We mon Data Analysis Problem by Marianna Paap to accompany The Cell: A ar h Seventh Edition Approac Geoffrey M. Cooper and Robert E. Hausman 2.3 The Effect of a Reducing Agent on Protein Structure Source: Janatova, J. 1986. Detection of disulphide bonds and localization of interchain linkages in the third (C3) and the fourth (C4) components of human complement. Biochem. J 233: 819-825. Corresponding chapter(s) in the textbook: Chapter 2 Review the following terms before working on the problem: tertiary and quaternary protein structure, chemical bonds, reducing agents, gel electrophoresis (SDS- PAGE), protein staining EXPERIMENT This experiment was designed to analyze the s and electrophoretic behavior of a of component (called C3c protein) of the complement system. The complement system consists various proteins in the blood plasma vertebrates and is involved in the immune response against microorganisms. Purified of kD) was incubated in the C3c protein (molecular agent, and then subjected presence of various concentrations of reducing Coomassie Brillant Blue, a oresis. The gel was stained with protein dye. The figure shows the molecular masses of intermediates and products generated by DTT treatment. FIGURE QUESTIONS 1. How many polypeptides are present in C3c? Determine their molecular masses from the figure. ply peptides 2. What was the purpose of using DTT in this experiment?Explanation / Answer
Answer:
1. There are 3 polypeptides of C3c. Their M.W. are 75 kDa, 43 kDa and 27 kDa.
(The lane with 10 mM DTT in the figure shows 3 bands.)
2. DTT is frequently used to reduce the disulfide bonds of proteins and peptides. It prevents intramolecular and intermolecular disulfide bonds from forming between cysteine residues of proteins.
The role of DTT in the experiment is to reduce the disulphide bonds between the polypeptides in C3c and help separate them as individual bands in SDS-PAGE gel.
3. C3c is made up 3 polypeptides covalently linked with S-S bond.
4. The 102 kDa polypeptide is produced through the linking of the 2 polypeptides - 75 kDa and 27 kDa through disulphide bonds.
(Since there many subparts, the first 4 subparts have been answered according to the rules of Chegg)
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