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The hisB gene, found in the enterobacteria (such as ''E. coli''), in ''Campylobacter jejuni'' and in ''Xylella''/''Xanthomonas'' encodes a protein involved in catalysis of two step in histidine biosynthesis (the sixth and eight step), namely the bifunctional Imidazoleglycerol-phosphate dehydratase/histidinol-phosphatase. The former function (), found at the N-terminal, dehydrated d-erythroimidazoleglycerolphosphate to imidazoleacetolphosphate, the latter function (), found at the C-terminal, dephosphorylates l-histidinolphosphate producing histidinol.〔Parker95: Parker, A.R., Moore, J.A., Schwab, J.M., Davisson, V.J. (1995). "Escherichia coli Imidazoleglycerol Phosphate Dehydratase: Spectroscopic Characterization of the Enzymic Product and the Steric Course of the Reaction." Journal of the American Chemical Society.〕 The firth step is catalysed instead by histadinolphosphate aminotransferase (encoded by ''hisC'') The peptide is 40.5kDa and associates to form a hexamer (unless truncated) In E. coli hisB is found on the hisGDCBHAFI operon The phosphatase activity possess a substrate ambiguity and overexpression of hisB can rescue phosphoserine phosphatase (serB) knockouts. == Reactions == hisB-N :D-erythro-1-(imidazol-4-yl)glycerol 3-phosphate 3-(imidazol-4-yl)-2-oxopropyl phosphate + H2O hisB-C :L-histidinol phosphate + H2O L-histidinol + phosphate 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「HisB」の詳細全文を読む スポンサード リンク
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