GATM and glioblastoma: It is ultimately converted into the final compound from the amino acids glycine and L-arginine. The enzyme EC 2.1.4.1 is the enzyme glycine aminotransferase (AGAT) and the enzyme EC 2.1.1.2 is the enzyme guanidinoacetate N-methyltransferase (GAMT). Both of these enzymes are elevated in patients with glioblastoma.