Question

multiple choice question
which of the following is not an amino acid?
a. isoleucine
b. valine
c. glutamate
d. thionate

Explanation:

Isoleucine (A) and Valine (B) are essential amino acids. Glutamate (C) is a non - essential amino acid. Thionate (D) is not an amino acid; it is a type of chemical ion or related to sulfur - containing chemical species, not an amino acid structure (which has an amino group and a carboxyl group along with a side chain).

Answer:

D. Thionate