1 U1K (S)-2-amino-3-(3-hydroxy-5-tert-butylisothiazol-4-yl) proprionic acid 1.000 2 CE2 3-(5-tert-butyl-3-oxidoisoxazol-4-yl)-L-alaninate 0.882 3 AMQ (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid 0.706