Amino Acid Mastery

A free alanine at physiological pH is:

Which of the following is closest to the [H+] concentration at physiological pH?

The isoelectric point (pI) of free glutamic acid is 3.22. At which pH would it be considered zwitterionic?

Which of the following amino acids would have the least amount of steric hindrance around its alpha carbon?

Which of the following amino acids is NOT aromatic?

Serine is classified as:

An enzyme that cleaves at the N-terminus of a branched amino acid would generate which of the following two peptide fragments when added to the peptide sequence FGLYTD?

A G6E mutation within a protein would result in which of the following?

The membrane-spanning portion of a transmembrane domain would contain which of the following pairs of amino acids?

Hexokinase uses side chain hydrogen bonding in its active site to bind glucose. Which of the following amino acids would be able to bind glucose in hexokinase’s active site?

Cysteine residues would form:

Which of the following is NOT true of a peptide bond?

Naturally occurring lysine has a measured specific rotation of +20.5 degrees. The non-naturally occurring form of lysine would have a specific rotation of:

Addition of proline to a protein would:

Which of the following amino acids is phosphomimetic?

Which amino acid contains a secondary amine?

What is the approximate weight of a tripeptide?

Which of the following amino acids has three ionizable sites?

The side chain of arginine contains nitrogens that are:

Free glycine would have which of the following IR stretches? I) 3300-3500 cm-1 II) 2950-3100 cm-1 III) 1650-1800 cm-1

Glucagon is a 29 amino acid peptide hormone responsible for maintaining blood glucose levels during fasting. The first five amino acids of its primary structure are HSNGT. What is the approximate mass of a mole of glucagon?

Glucagon is a 29 amino acid peptide hormone with a net charge of 0 at physiological pH. Which of the following is true of glucagon at physiological pH?

Glucagon is a 29 amino acid peptide hormone. The first five amino acids are HSNGT. The first N-terminal amino acid of glucagon is classified as:

Glucagon is a 29 amino acid peptide hormone. The first five amino acids are HSNGT. How many of glucagon’s first five N-terminal amino acids could be phosphorylated?

Glucagon is a 29 amino acid peptide hormone. The first five amino acids are HSNGT. What is the net charge of the side chains of the first five amino acids at physiological pH?

Calmodulin is a small protein with a flexible linker region between two globular domains. Which of the following amino acids would you expect to find in the flexible linker?

Calmodulin contains EF motifs that bind calcium ions. Which amino acids would be found in the EF motif binding region?

Calmodulin lacks an alpha helix at its N-terminus. Troponin C is structurally similar but has an alpha helix at its N-terminus. Troponin C is unlikely to have which of the following amino acids near its N-terminus?