(L)-Histidine (S)-2-Amino-3-(4-imidazolyl)propionsaeure (S)-4-(2-Amino-2-carboxyethyl)imidazole (S)-alpha-Amino-1H-imidazole-4-propanoic acid 150-35-6 155304-24-8 1H-Imidazole-4-alanine,