Glutamine
In human blood, glutamine is the most abundant free amino acid.
Aminoacylase 1 deficiency
Aminoacylase 1 (ACY1: EC 3.5.14) is a zinc binding enzyme which hydrolyzes N-acetyl amino acids into the free amino acid and acetic acid. Of the N-actyl amino hydrolyzing enzymes, aminoacylase 1 is the most common.