QUESTION. Which four of the following statements about amino acids are true? A chart of amino acid structures can be found here. a. The form of glycine used by the human body is D-glycine. b. The Val side chain does not form hydrogen bonds with other amino acids. c. Methionine is a thiol. d. Phe can undergo oxidation to form Tyr. e. Alanine has an overall charge at physiological pH (7.4). f. Asn and Gin are polar amino acids. g. Methionine has one stereocenter (chiral center).