Is this amino acid L- or D-, and how can you tell?
A) L-, because all amino acids are L.
B) D-, because all amino acids are D.
C) D-, because the amine is on the right.
D) D-, because the amine is on the left.
E) L-, because the amine is on the left.

Question

Is this amino acid L- or D-, and how can you tell? 
A) L-, because all amino acids are L. 
B) D-, because all amino acids are D. 
C) D-, because the amine is on the right. 
D) D-, because the amine is on the left. 
E) L-, because the amine is on the left.

Quizplus · Accepted Answer

The amine group in amino acids is always on the left in L-form amino acids and on the right in D-form amino acids. Therefore, since the amine group is on the right in the given structure, it is a D-amino acid. Options A and B are incorrect because not all amino acids are L or D-form, respectively. Option D is also incorrect because the amine group is not on the left. Option E is incorrect because the given structure is not a L-amino acid as the amine group is on the right.

Is This Amino Acid L- or D-, and How Can