Characterization of mammalian sedoheptulokinase and mechanism of formation of erythritol in sedoheptulokinase deficiency.
Our aim was to identify the product formed by sedoheptulokinase and to understand the mechanism of formation of erythritol in patients with sedoheptulokinase deficiency. Mouse recombinant sedoheptulokinase was found to be virtually specific for sedoheptulose and its reaction product was identified as sedoheptulose 7-phosphate. Assays of sedoheptulose in plant extracts disclosed that this sugar is present in carrots ( approximately 7mumol/g) and in several fruits. Sedoheptulose 1-phosphate is shown to be a substrate for aldolase B, which cleaves it to dihydroxyacetone-phosphate and erythrose. This suggests that, in patients deficient in sedoheptulose-7-kinase, sedoheptulose is phosphorylated by fructokinase to sedoheptulose 1-phosphate. Cleavage of the latter by aldolase B would lead to the formation of erythrose, which would then be reduced to erythritol.
Kardon
Tamas
T
Laboratory of Physiological Chemistry, de Duve Institute, Université Catholique de Louvain, Ave. Hippocrate 75, B-1200 Brussels, Belgium.
Stroobant
Vincent
V
Veiga-da-Cunha
Maria
M
Schaftingen
Emile Van
EV
D000818:Animals; D004896:Erythritol / Q000096:biosynthesis*; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry; D005638:Fruit / Q000201:enzymology; D006801:Humans; D051379:Mice; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013403:Sugar Phosphates / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000172:deficiency / Q000235:genetics; D014675:Vegetables / Q000201:enzymology
D010940:Plant Proteins; D011994:Recombinant Proteins; D013403:Sugar Phosphates; D014157:Transcription Factors; C020495:sedoheptulose 7-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C404793:SHPK protein, human; C533417:Shpk protein, mouse; D005634:Fructose-Bisphosphate Aldolase; D004896:Erythritol