D-ERYTHRO-IMIDAZOLE-GLYCEROL-P D-erythro-1-(imidazol-4-yl)-glycerol-3-phosphate D-erythro-imidazole-glycerol-phosphate IGP erythro-imidazole-glycerol-P erythro-imidazole-glycerol-phosphate imidazole glycerol phosphate