Final Exam B, Problem 6 | MIT 3.091SC Introduction to Solid State Chemistry, Fall 2010

TL;DR

The video discusses the structure of a dipeptide and explains the tertiary structure of proteins, including the chemical interactions involved.

Transcript

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Key Insights

• ❓ A dipeptide consists of two amino acids joined by a peptide bond.
• 👥 The position of the peptide bond in a dipeptide is between the amine group of one amino acid and the carboxyl group of the other.
• 👥 Extreme basicity deprotonates both the amine and carboxylic acid groups in alanine and serine, resulting in a deprotonated amine group and a deprotonated carboxyl group.
• ❓ The tertiary structure of a protein is determined by various chemical interactions, including disulfide bonds, hydrogen bonds, electrostatic interactions, and hydrophobic interactions.
• 🥵 Extreme heat can disrupt disulfide bonds, while acid can disrupt hydrogen bonds.
• 👥 To disrupt electrostatic interactions, the carboxylic acid or amine group can be reprotonated or deprotonated.

Questions & Answers

Q: What is a dipeptide, and how can we distinguish it from a single amino acid?

A dipeptide is formed when two amino acids are joined together by a peptide bond. It is distinguished from a single amino acid by the presence of two amine and two carboxyl groups.

Q: How does extreme basicity affect the structure of alanine and serine in an aqueous solution?

Extreme basicity causes the amine group and carboxylic acid group of both alanine and serine to become deprotonated in an aqueous solution. This results in the formation of a deprotonated amine group and a deprotonated carboxyl group.

Q: Why is the hydrogen attached to the oxygen in the side chain of serine not deprotonated in an aqueous solution with extreme basicity?

The pKa of alcohol, such as the hydroxyl group in serine, is around 16, which means that it does not get deprotonated in an aqueous solution with extreme basicity. Therefore, the hydrogen remains attached to the oxygen in this solution.

Q: What are the four types of chemical interactions that contribute to the tertiary structure of the protein chain?

The four types of chemical interactions mentioned are disulfide bond, hydrogen bond, electrostatic interaction, and hydrophobic interaction.

Summary & Key Takeaways

• The video explains the structure of a dipeptide derived from alanine and serine, highlighting that it has two amine and two carboxyl groups.

• It discusses the position of the peptide bond in the dipeptide, emphasizing that it is the bond between the amine group of one amino acid and the carboxyl group of the other.

• The video then delves into the skeletal structure of alanine and serine in an aqueous solution with extreme basicity (pH greater than 12), discussing the deprotonation of the amine and carboxylic acid groups.