Which amino acid contains neither sulfur nor nitrogen in its side chain?

Which level of protein structure is described by the association of multiple subunits into a functional multimeric protein?

Which of the following is not a nonpolar amino acid?

A small synthetic peptide is composed of three amino acids: arginine (pKa = 12.48), lysine (pKa = 10.54), and aspartate (pKa = 3.90). Under normal physiological conditions (pH = 7.4), what will be the overall charge of this peptide? Note: the pKa values are for the side chains.

How many distinct tetrapeptides can be made from one unit each of Asp, Trp, Phe, and Arg?

Phenylketonurics have a deficiency of phenylalanine hydroxylase. Which of the following describes the effect of this deficiency?

All Amino Acids are considered amphoteric.

If a substance is said to be amphoteric, what is true of this substance?

A researcher denatures a polypeptide. What can you conclude about this denatured polypeptide?

Which of the following amino acids is nonpolar?

Protein I has a molecular weight of and a pI of 6.5, protein II has a molecular weight of and a pI of 8.0, and protein III has a molecular weight of and a pI of 10.5.

If a sample containing proteins I, II, and III is run through a DEAE ion exchange column at pH 7.5, and the column is eluted with a gradient, what is the order of elution?