Exam 22: Amino Acids, Peptides, and Proteins

Give a detailed, stepwise mechanism for the formation of the activated acyl derivative from the reaction of an amino acid with N,N'-dicyclohexylcarbodiimide.

Treatment of a decapeptide with Edman's reagent releases PTH-Ala. What conclusion can be drawn regarding the decapeptide's primary structure?

What is the major force responsible for the formation of an α-helix in protein secondary structure?

Which labeled bond in the following molecule is known as the peptide bond?

Give the product for the following reaction.

What are enzymes?

In nature, which is the most commonly found isomer, L-amino acids or D-amino acids?

Provide the structure of the tripeptide val-gly-ser at pH 12.

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents:? 1. PBr₃, Br₂; 2) H₂O; 3) NH₃, Δ?

Which of the following molecules is the skeletal structure of an amino acid?

Draw a line where cleavage occurs with chymotrypsin.

In a globular protein, would the side chain of isoleucine most probably be oriented toward the interior of the protein or outward toward the aqueous surroundings? Explain.

In a globular protein, would the side chain of aspartic acid most probably be oriented toward the interior of the protein or outward toward the aqueous surroundings? Explain.

Provide the Fischer projection of L-aspartic acid.

Consider the two peptides shown below. Which of the following methods would be able to distinguish between these two sequences? Ala-Met-Val-Leu-Gly-Gly-Phe-Glu-Arg-Val And Ala-Val-Gly-Glu-Val-Met-Leu-Gly-Arg-Phe

Explain the chemistry behind giving a "permanent" to a head of hair.

Which of the following amino acids has a sulfur in the R group?

What amino acid can be obtained by the reductive amination of γ-ketoglutaric acid, HO₂CCH₂CH₂COCO₂H?

Which of the following terms best describes the side chain of valine?

Provide the structure of the tripeptide val-gly-ser at pH 2.