What kind of biological function would each of the following proteins perform?
a. Human growth hormone

Glycine has the zwitterion structure shown. Draw the structure and give the net charge of glycine that will predominate at the indicated pH values (pI = 6.0).

a. pH 1.5

Two of the 20 common amino acids have two chiral carbon atoms in their structures. Identify these amino acids and their chiral carbon atoms.

Which would you expect to be more soluble in water, a peptide containing mostly alanine and leucine or a peptide containing mostly lysine and aspartic acid? Explain. (Hint: Consider side-chain interactions with water.)

What kind of biological function would each of the following proteins perform?

c. Protease

Name four biological functions of proteins in the human body, and give an example of a protein for each function.

Cortisol levels rise under stressful conditions. Oxytocin can induce relaxation and romantic feelings. What type of protein are cortisol and oxytocin?

Alcohol dehydrogenase, found in liver cells, converts ethanol into acetaldehyde. What type of protein is alcohol dehydrogenase?

Draw the structure of the following amino acids, dipeptides, and tripeptides at low pH (pH 1) and high pH (pH 14). At each pH, assume that all functional groups that might do so are ionized.

d. Glu-Asp