TBR Bio Question Ch. I Psg. X

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Question shows a drawing of GABA and asks for its IUPAC name:

a. y-amino butyrate
b. 3-amino butanoic acid
c. 1-amino butyrate
d. 4-aminobutanoic acid

The drawing as shown has a positive amino group at one end and deprotonated COO- at the other. I was thinking of putting D which is the correct answer but put C. Even though the naming of the amino group is wrong, isn't the butyrate hinting its the deprotonated form? Or am I wrong?

The protonation state of the amino and carboxylic acid groups is dependent on the pH of the solution that the species is in and is irrelevant to nomenclature. At biological pH the amino group will be protonated and the carboxylic acid will be deprotonated, which is important to recognize.

If you're specifically talking about the conjugate base of a butyric acid salt, then it would be butyrate.

The butyrate does hint at the deprotonated form; however, the carbonyl on the carboxylic acid gets priority when it comes to naming. Hence, the amino group is located on carbon #4 and not carbon #1, which is why answer D is the answer.