Histidinol dehydrogenase

This enzyme [EC 3.5.4.19] catalyzes the hydrolysis of 5-phosphoribosyl-AMP to produce 5-(5-phospho-D-ribo-sylaminoformimino)-l-(5-phosphoribosyl)tmidazole-4-carboxamide. The enzyme isolated from Neurospora crassa can also catalyze the reactions of histidinol dehydrogenase and phosphoribosyl-ATP pyrophosphatase. 

HISTAMINE N-METHYLTRANSFERASE HISTIDINE AMMONIA-LYASE DEHYDROALANINE HISTIDINE DECARBOXYLASE Histidine decarboxylase reduction, BOROHYDRIDE REDUCTION HISTIDINOL DEHYDROGENASE... 

GLYOXYLATE REDUCTASE HISTIDINOL DEHYDROGENASE HOMOISOCITRATE DEHYDROGENASE HOMOSERINE DEHYDROGENASE HYDROGEN DEHYDROGENASE... 

E. Coli L-histidinol Dehydrogenase Octahedral Zinc Site... 

E. coli L-histidinol dehydrogenase IKAE 1 Gln 2 HiSaa 97 Aspa HiSa free His... 

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

CpG0141 Histidinol dehydrogenase C0Gbl40 Phosphoribosyl-ATP pyrophosphol-... 

CQG0139 Phosphoribosyl-AHP cyclohydrolr CQG0141 Histidinol dehydrogenase... 

Evidence for the presence of the enzymes of the histidine pathway in plants appears to be limited to the work of Winter et al. (1971a) who demonstrated the presence of ATP-phosphoribosyltransferase, the first enzyme of the pathway, imidazole glycerolphosphate dehydratase and histidinol phosphatase in extracts from the shoots of barley, oats, and peas, and to the unpublished observations of Davies (see Davies, 1971) on the presence of histidinol dehydrogenase in rose tissue culture cells. The specific activity of ATP-phosphoribosyltransferase was greatest in peas and oats and least in barley. The enzymes from oats and barley were thermolabile losing activity after 30 min at 37°C. The specific activities of imidazole glycerolphosphate dehydratase were very low but it was possible to purify the enzyme to some extent. The values for imidazole glycerolphosphate for the barley enzyme was 0.6 mM which compares with values for jthe yeast and bacterial enzymes of 0.3 and 0.4 mM, respectively. Histidinolphosphatase was purified 20-fold but the authors considered that two phosphatases were still present. 

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.

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... 

Histidinol is oxidized to histidine by a dehydrogenase that appears to catalyze both steps required. - The most definitive studies on this dehydrogenase were carried out with preparations of Arlhrobacter hi i-dinolovorans, a soil organism isolated by an enrichment technique using histidinol as a carbon and nitrogen source. Similar enzymes occur in E. coli and yeast. Two equivalents of DPNH are produced in this reaction. The reduction of the first mole of DPN by these enzymes should result in the formation of the aldehyde, histidinal. This compound, however, has not been detected in incubation mixtures, even when aldehyde binders were added. Histidinal, an unstable compound in neutral solution, does serve as a substrate for the dehydrogenase, with both DPN... 

AflSnity chromatographic purification 192 of adenosine triphosphatase from rat liver mitochondria Affinity chromatographic purification 193 of adenosine deaminase Affinity chromatographic purification 194 of histidinol dehydrogenase Purification of dehydrogenase 195... 

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