(alpha-Carboxycyclopropyl)glycine 2-(Carboxycyclopropyl)glycine 22255-17-0 3,4-Cyclopropylglutamate CCPG Cyclopropaneacetic acid, alpha-amino-2-carboxy- L-2-(Carboxypropyl)glycine L-Ccg-I alpha-(Carboxycyclopropyl)glycine alpha-Amino-2-carboxycyclopropaneacetic acid