Imidazole acetol phosphate

The enzymes that catalyze these transformations have been partially purified from extracts of Neurospora. Imidazole glycerol phosphate is dehydrated by an enzyme named IGP dehydrase to form imidazole acetol phosphate. The dehydrase requires Mn++ and a sulfhydryl com-... 

The conversion of imidazole acetol phosphate to histidinol phosphate is catalyzed by a transaminase. This pyridoxal phosphate enzyme reacts... 

Relative Rates of Reaction ivith Imidazole Acetol Phosphate Tkansaminasb ... 

Compound Imidazole acetol phosphate a-Ketoglutarate of-Keto-5- a-Ketoadipate guanidovalerate ... 

The herbicide Amitrole (455) has several documented effects on metabolism. In E. coli, histidine and adenine together reverse the inhibition of growth by Amitrole, whereas adenine alone, but not histidine alone, partially relieves the inhibition. In the yeast T. cremoris, histidine alone, but not adenine alone, completely reverses the inhibition.A metabolite, identified as a conjugate of alanine and Amitrole, has been shown to accumulate in the medium of E. coli cultured in the presence of Amitrole it apparently competes with histidine for incorporation into protein.Unlike Amitrole, this metabolite does not inhibit the conversion of imidazole glycerol phosphate (IGP) to imidazole acetol phosphate by IGP dehydratase in Salmonella the reaction is part of the biosynthesis of histidine. 

Fig. 4. Histidine tnosynthess. Intermediates PRPP, phosphoribosyl pyrophosidiate PR-ATP, JV-phoqjhoribosyl-ATP PR-AMP, A/ -phosphoribosyl-AMP PR-FAIC-RN, phosphoribosyl for-mimino-S-amino imidazole carboxamide ribonucleotide PRu-FAIC-RN, phosphoribulosyl for-mimino-5-aniino imidazole carboxamide ribonucleotide IGP, imidazole glycerol phosphate lAP, imidazole acetol idrosphate HP, histidinol (dioqrhate HOL, histidinol. Enzymes (I) ATP phos-phoribosyltransferase (EC 2.4.2.17) (2) phosphoribosyl-ATP pyrophosphohydrolase (EC 3.6.1.31) (3) idiospharibosyl-AMP cyciohydrolase (EC 3.5. A19) (4) PR-FAIC-RN isomerase (EC S.3.1.16) (S) glutamine amidotransferase (6) cyclase (7) imidazole glycerol phosphate dehydratase (EC 4.2.1.19) (8) histidinol-phosphate aminotransferase (EC 2.6.1.9) (9) histidinol phosphatase (EC 3.1.3.15) (10) histidinol dehydrogenase (EC 1.1.1.23).

---