1 85G N-ethyl-L-glutamine 1.000 2 85J N-propyl-L-glutamine 0.923 3 MEQ N5-methylglutamine 0.917 4 9R7 L-gamma-glutamylglycine 0.857 5 ILO N5-iminoethyl-L-ornithine 0.846 6 ORQ N~5~-acetyl-L-ornithine 0.846 7 QMM N,N-dimethyl-L-glutamine 0.846 8 4JK (S)-2-amino-5-(2-hydroxyacetimidamido)pentanoic acid 0.786 9 AHO N-acetyl-N-hydroxy-L-ornithine 0.786 10 FIO N~5~-[(1e)-2-fluoroethanimidoyl]-L-ornithine 0.786 11 LN5 N5-(1-iminopropyl)-L-ornithine 0.786 12 VUR (S)-2-amino-5-(2-mercaptoacetimidamido)pentanoic acid 0.786 13 WT2 (S)-2-amino-5-(2-oxoacetimidamido)pentanoic acid 0.786 14 1HB (4s)-4-amino-5-hydroxy-N,N-dimethylpentanamide 0.769 15 HGA Glutamine hydroxamate 0.769 16 3GC Gamma-glutamylcysteine 0.750 17 9R4 D-gamma-glutamyl-2-methyl-L-alanine 0.750 18 AA4 2-amino-5-hydroxypentanoic acid 0.750 19 JM2 N~5~-[2-(methylsulfanyl)ethanimidoyl]-L-ornithine 0.733 20 VIO N5-(1-imino-3-butenyl)-L-ornithine 0.733 21 4VI (2z,4e)-5-carbamimidamido-2-iminopent-4-enoic acid 0.714 22 AR7 Amino{[(4s)-4-amino-5,5-dihydroxypentyl]amino}methaniminium 0.714 23 ARG Arginine 0.714 24 CIR Citrulline 0.714 25 DAR D-arginine 0.714 26 FH7 N^5^-formyl-N^5^-hydroxy-D-ornithine 0.714 27 FHO N^5^-formyl-N^5^-hydroxy-L-ornithine 0.714 28 GND 2-amino-5-guanidino-pentanoic acid 0.714 29 IAR (2e)-5-[(diaminomethylidene)amino]-2-iminopentanoic acid 0.714 30 SCI L-thiocitrulline 0.714