Article (Scientific journals)
The Compartmentation of Phosphorylated Thiamine Derivatives in Cultured Neuroblastoma Cells
Bettendorff, Lucien
1994In Biochimica et Biophysica Acta, 1222 (1), p. 7-14
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Abstract :
[en] Thiamine transport in cultured neuroblastoma cells is mediated by a high-affinity carrier (KM = 40 nM). In contrast, the uptake of the more hydrophobic sulbutiamine (isobutyrylthiamine disulfide) is unsaturable and its initial transport rate is 20-times faster than for thiamine. In the cytoplasm, sulbutiamine is rapidly hydrolyzed and reduced to free thiamine, the overall process resulting in a rapid and concentrative thiamine accumulation. Incorporation of radioactivity from [14C]thiamine or [14C]sulbutiamine into intracellular thiamine diphosphate is slow in both cases. Despite the fact that the diphosphate is probably the direct precursor for both thiamine monophosphate and triphosphate, the specific radioactivity increased much faster for the latter two compounds than for thiamine diphosphate. This suggests the existence of two pools of thiamine diphosphate, the larger one having a very slow turnover (about 17 h); a much smaller, rapidly turning over pool would be the precursor of thiamine mono- and triphosphate. The turnover time for thiamine triphosphate could be estimated to be 1-2 h. When preloading the cells with [14C]sulbutiamine was followed by a chase with the same concentration of the unlabeled compound, the specific radioactivities of thiamine and thiamine monophosphate decreased exponentially as expected, but labeling of the diphosphate continued to increase slowly. Specific radioactivity of thiamine triphosphate increased first, but after 30 min it began to slowly decrease. These results show for the first time the existence of distinct thiamine diphosphate pools in the same homogeneous cell population. They also suggest a complex compartmentation of thiamine metabolism.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Bettendorff, Lucien  ;  Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Biochimie et physiologie humaine et pathologique
Language :
English
Title :
The Compartmentation of Phosphorylated Thiamine Derivatives in Cultured Neuroblastoma Cells
Publication date :
1994
Journal title :
Biochimica et Biophysica Acta
ISSN :
0006-3002
eISSN :
1878-2434
Publisher :
Elsevier, Amsterdam, Netherlands
Volume :
1222
Issue :
1
Pages :
7-14
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 23 January 2009

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