Exam 27: Amino Acids and Proteins

What fragments are produced when porcine dynorphin, a peptide that contains 17 amino acid residues (shown below), is cleaved with trypsin? Tyr−Gly−Gly−Phe−Leu−Arg−Arg−Ile−Arg−Pro−Lys−Leu−Lys−Trp−Asp−Asn−Gln

Edman degradation of the peptide saralasin shows that it has a sarcosine residue at the N-terminus. Sarcosine is Partial hydrolysis of saralasin with dilute hydrochloric acid gives the following fragments: His−Pro−Ala Val−Tyr−Val Arg−Val−Tyr Sar−Arg−Val Tyr−Val−His What is the structure of saralasin?

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is a polypeptide which gives four fragments on treatment with chymotrypsin.

What are the R/S designations of the two stereocenters of isoleucine?

Which of the following tripeptides is not hydrolyzed by chymotrypsin?

Structure _____ (shown below) will remain at the origin in an electrophoresis experiment. | | | I II III

Which of the following amino acids has a polar side chain?

In Cys-Ile-Ser-Asp-Gly-His-Gly-Gly, the three-letter abbreviation for the N-terminal amino acid is ________.

What is the approximate value of the pK_a of the α-CO₂H of amino acids?

What is the major organic product of the following reaction?

What fragments are produced when porcine dynorphin, a peptide that contains 17 amino acid residues (shown below), is cleaved with chymotropsin? Tyr−Gly−Gly−Phe−Leu−Arg−Arg−Ile−Arg−Pro−Lys−Leu−Lys−Trp−Asp−Asn−Gln

The number of different combinations that are possible for a tripeptide containing one of each of the following amino acids: Phe, Val, Asp is ______.

Which of the following is not a polypeptide?

Which of the following amino acids has a basic side chain?

Provide the structure of Ser-Phe-Asp.

Provide the structure of dicylcohexylcarbodiimide, a common reagent that is used to couple two amino acid residues by formation of a peptide bond, and the structure N,N'-dicyclohexylurea, the byproduct of this reaction.

Consider the following octapeptide. Ala-Val-Trp-Lys-Phe-Gly-Arg-Met The fragments that would be obtained by a trypsin hydrolysis are Ala-Val-Trp-Lys and Phe-Gly-Arg and Met.

Disulfide bonds form between the thiol side chains of cysteine. What is the best term to describe the reaction of two thiols to give a disulfide bond?

MATCH a structure from the list below to each of the following terms. Place the letter of the structure in the blank to the left of the term which it describes. -_____ is an amino acid in its zwitterionic form.

Which of the following natural amino acids is an R-isomer?