Which of the following describes amino acids with aromatic R-roups?

An unknown amino acid has been isolated from a solution. It has a charge at a pH of 12. It shows 3 equivalent points on its titration curve, and is found to have amphipathic properties. Which amino acid is this?

Which amino acid(s) contain(s) sulfur?

Which of the following is a characteristic of selenocysteine?

Which of the following amino acids have side chains capable of hydrogen bonding interactions?

I. Alanine

II. Aspartate

III. Threonine

IV. Methionine

How many water molecules are produced upon synthesis of myoglobin, a 154-amino acid protein?

Which of the following amino acids is positively charged in a solution with pH 7.0?

A researcher is analyzing a transmembrane protein found on cell membranes. He observes lots of valine residues on the membrane spanning portion of the protein. What can you conclude about these results?

A protein in aqueous solution is run through a column containing negatively charged beads. A small amount of protein is found to be inside the column after the mobile phase has finished running. Which of the following amino acids is probably found in higher concentration within this small amount of protein?

Suppose that an amino acid with pI = 10.4 in acidic solution is titrated with a strong base, . What will the net charge of this amino acid be at a pH of 2, 8, and 12?