1. 2.1.3.3 enzyme   ornithine carbamoyltransferase
                      ornithine carbamyltransferase
                      ornithine transcarbamylase
                      L-ornithine carbamoyltransferase
                      L-ornithine carbamyltransferase
                      L-ornithine transcarbamylase
                      carbamylphosphate-ornithine transcarbamylase
                      carbamoyl-phosphate:L-ornithine carbamoyltransferase
                      OTC
                      citrulline phosphorylase

2. 2.3.1.127 enzyme   ornithine N-acyltransferase
                      ornithine N-benzoyltransferase
                      benzoyl-CoA:L-ornithine N-benzoyltransferase

3. 2.3.1.35 enzyme   ornithine acetyltransferase
                      ornithine transacetylase
                      acetylglutamate-acetylornithine transacetylase
                      acetylglutamic-acetylornithine transacetylase
                      acetylornithine glutamate acetyltransferase
                      N2-acetyl-L-ornithine:L-glutamate N-acetyltransferase
                      alpha-N-acetyl-L-ornithine:L-glutamate N-acetyltransferase
                      acetylornithinase
                      acetylglutamate synthetase
                      acetylglutamic synthetase
                      glutamate acetyltransferase
                      N-acetylglutamate synthase
                      N-acetylglutamate synthetase
                      glutamate N-acetyltransferase
                      N-acetyl-L-glutamate synthetase

4. 2.6.1.13 enzyme   ornithine transaminase
                      L-ornithine aminotransferase
                      ornithine 5-aminotransferase
                      ornithine delta-transaminase
                      ornithine-ketoglutarate aminotransferase
                      L-ornithine 5-aminotransferase
                      ornithine-2-oxoacid aminotransferase
                      ornithine-alpha-ketoglutarate aminotransferase
                      ornithine-keto acid aminotransferase
                      ornithine-keto acid transaminase
                      ornithine-oxo acid aminotransferase
                      ornithine-oxo-acid transaminase
                      ornithine:alpha-oxoglutarate transaminase
                      L-ornithine:2-oxo-acid aminotransferase
                      L-ornithine:alpha-ketoglutarate delta-aminotransferase
                      OAT

5. 3.1.1.48 enzyme   ornithine esterase
                      fusarinine-C ornithinesterase
                      N5-acyl-L-ornithine-ester hydrolase

6. 4.1.1.17 enzyme   ornithine decarboxylase
                      L-ornithine carboxy-lyase

7. 4.3.1.12 enzyme   ornithine cyclase
                      ornithine cyclodeaminase
                      ornithine cyclase (deaminating)
                      L-ornithine ammonia-lyase (cyclizing)

8. 5.1.1.12 enzyme   ornithine racemase
                      ornithine racemase

9. 5.4.3.5 enzyme   D-ornithine aminomutase
                      D-ornithine 4,5-aminomutase
                      D-ornithine 4,5-aminomutase
                      D-alpha-ornithine 5,4-aminomutase

10. 1.5.1.24 enzyme   N5-(carboxyethyl)ornithine synthase
                      N5-(L-1-carboxyethyl)-L-ornithine:NADP+ oxidoreductase (L-ornithine-forming)

11. 2.6.1.68 enzyme   ornithine(lysine) aminotransferase
                      ornithine(lysine) transaminase
                      L-ornithine:2-oxoglutarate-aminotransferase
                      lysine/ornithine:2-oxoglutarate aminotransferase
                      L-ornithine(L-lysine):2-oxoglutarate-aminotransferase

12. 3.5.1.16 enzyme   acetylornithine deacetylase
                      N2-acetyl-L-ornithine amidohydrolase
                      acetylornithinase
                      N-acetylornithinase

13. 2.6.1.11 enzyme   acetylornithine aminotransferase
                      acetylornithine transaminase
                      succinylornithine aminotransferase
                      N-acetylornithine aminotransferase
                      acetylornithine 5-aminotransferase
                      acetylornithine delta-transaminase
                      N-acetylornithine-delta-transaminase
                      N2-acetylornithine 5-transaminase
                      N2-acetyl-L-ornithine:2-oxoglutarate aminotransferase
                      N2-acetyl-L-ornithine:2-oxoglutarate 5-aminotransferase
                      ACOAT

14. 2.6.1.81 enzyme   succinylornithine aminotransferase
                      succinylornithine transaminase
                      N2-succinylornithine 5-aminotransferase
                      2-N-succinyl-L-ornithine:2-oxoglutarate 5-aminotransferase
                      AstC
                      SOAT

15. 2.1.3.9 enzyme   acetylornithine transcarbamylase
                      N-acetylornithine carbamoyltransferase
                      N-acetylornithine transcarbamylase
                      carbamoyl-phosphate:2-N-acetyl-L-ornithine carbamoyltransferase
                      AOTC