Phosphatase histidinol phosphate

HISTIDINOL-PHOSPHATE PHOSPHATASE HISTIDYL-tRNA SYNTHETASE HISTONE KINASE Hofmann rule,... 

GLYCOGEN PHOSPHORYLASE HISTIDINOL-PHOSPHATE PHOSPHATASE myo-INOSITOL 1-MONOPHOSPHATASE... 

SL-histidinol phosphate aminotransferase histidinol phosphate phosphatase ( histidinol dehydrogenase... 

Fig. 2. The pathway of histidine biosynthesis. Enzymes a, ribosephosphate pyrophos-phokinase E.C. 2.7.6.1 b, ATP-phosphoribosyltransferase, E.C. 2.4.2.17 c, phosphoribosyl-AMP cyclohydrolase, E.C. 3.5.4.19 d, N-(5 -phospho-D-ribosylforminino)5-amino-l-(5"-phos-phoribo yl)-4-imidazole carboxamide isomerase, E.C. 5.3.1.16 e, glutamine amidotransferase f, imidazolglycerolphosphate dehydratase E.C. 4.2.1.19 g, histidinol-phosphate aminotransferase E.C. 2.6.1.9 h, histidinol phosphatase, E.C. 3.1.3.15 i, histidinol dehydrogenase, E.C. 1.1.1.23.

Values are for the specific activity of histidinol phosphate phosphatase relative to the level in the parent strain grown on minintal salts-glucose. The data are taken from Klopotowski and Ames [1171 and Roth et al. [15]. 

ATP phosphoribosyltransferase 2 phosphoribosyl-ATP pyrophosphatase 3 phosphoribosyl-AMP cyclohydrolase 4 isomerase 5 formyltransferase, inosine monophosphate cyclohydrolase 6 adenylosuccinate synthetase 7 adenylosuccinate lyase 8 adenylate kinase 9 imidazole glycerol phosphate dehydratase 10 histidinol phosphate aminotransferase 11 histidinol phosphatase 12 histidinol dehydrogenase... 

The conversion of histidinol phosphate to histidine requires removal of the phosphate group free histidinol was the first precursor of histidine established in genetic studies. The hydrolysis of histidinol phosphate is catalyzed by a phosphatase that has recently been purified by Ames from Neurospora extracts. This enzyme is active with histidinol phosphate as a substrate, but has very little, if any, activity with a number of phosphate esters, including the other imidazole compounds involved in histidine biosynthesis. At least one less specific phosphatase occurs in Neurospora histidinol phosphate is also hydrolyzed nonspecifically, but the activity of the nonspecific hydrolytic enzyme is slow compared with the specific histidinol phosphatase. The nonspecific reaction may account for the slow growth of mutants deficient in the specific enzyme. The specific enzyme is quite insensitive to beryllium and chelating agents, which inhibit nonspecific phosphate hydrolysis. 

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).

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