Essential amino acid is
A semi-essential amino acid that occurs in proteins and is involved in the urea cycle and in the synthesis of creatine. Preparations of the base or the glutamate or hydrochloride salt are used in the treatment of <a href=" and in the assessment of pituitary function.</p>Ref: Harper&;s Illustrated Biochemistry, 26th edition, page no: 237
Alanine
Serine
Arginine
Proline
Structure and function of protein