Identify acidic amino acid from following list represented by three letter symbols.

Step-by-step solution

Amino acids are classified based on their side chain properties as neutral (polar or non-polar), acidic, or basic. Among the given options: Threonine has a polar hydroxyl group, making it neutral polar. Tryptophan's indole ring classifies it as neutral non-polar. Histidine contains an imidazole group that can accept protons, classifying it as basic. Glutamic acid possesses an additional carboxyl group in its side chain that donates protons, making it acidic.