29. Amino Acids

In a pulse-chase experiment, which type of proteins are typically radioactively labeled to study their synthesis and degradation?

Which codon specifies the amino acid methionine in protein synthesis?

Three peptides were obtained from a trypsin digestion of two different polypeptides. In each case, indicate the possible sequences from the given data and tell what further experiment should be carried out in order to determine the primary structure of the polypeptide.

a. polypeptide I:

1. Val-Gly-Asp-Lys

2. Leu-Glu-Pro-Ala-Arg

3. Ala-Leu-Gly-Asp

How many calories per $g$ are provided by proteins?

Which of the following is a monomer of a protein?

Show how you would synthesize any of the standard amino acids from each starting material. You may use any necessary reagents.

(a)

Draw the tetrapeptide Ala-Thr-Asp-Asn and indicate the peptide bonds.

For each compound,

1. name the functional group.

2. show what compound(s) result from complete hydrolysis.

(c)

After the polypeptide shown below was treated with maleic anhydride, it was hydrolyzed by trypsin. (After a polypeptide is treated with maleic anhy- dride, trypsin will cleave the polypeptide only on the C-side of arginine.)

Gly-Ala-Asp-Ala-Leu-Pro-Gly-Ile-Leu-Val-Arg-Asp-Val-Gly-Lys-Val-Glu-Val-Phe-Glu-Ala-Gly- Arg-Ala-Glu-Phe-Lys-Glu-Pro-Arg-Leu-Val-Met-Lys-Val-Glu-Gly-Arg-Pro-Val-Gly-Ala-Gly-Leu-Trp

a. After a polypeptide is treated with maleic anhydride, why does trypsin no longer cleave it on the C-side of lysine?

b. How many fragments are obtained from the polypeptide?

Which of the following is not a component of an amino acid molecule?

What effect would a mutation have on a protein if the DNA codon sequence $\text{GTT}$ changes to $\text{GTC}$?

How many nucleotides are needed to specify $3$ amino acids in a protein sequence?

What differentiates one amino acid from another?

Show how you would use a Strecker synthesis to make phenylalanine.

How are two amino acids typically linked together in a protein structure?