Article (Scientific journals)
Metabolism of Thiamine Triphosphate in Rat Brain: Correlation with Chloride Permeability
Bettendorff, Lucien; Peeters, Maryline; Wins, Pierre et al.
1993In Journal of Neurochemistry, 60 (2), p. 423-434
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Abstract :
[en] Our results show that a net synthesis of thiamine triphosphate (TTP) can be demonstrated in vitro using rat brain extracts. The total homogenate was preincubated with thiamine or its diphosphate derivative (TDP), centrifuged, and washed twice. With TDP (1 mM) as substrate, a 10-fold increase in TTP content was observed in this fraction (nuclear fraction, membrane vesicles). A smaller, but significant, increase was observed in the P2 fraction (mitochondrial/synaptosomal fraction). In view of the low TTP content of our fractions, it was carefully assessed that authentic TTP was being formed. Incorporation of radioactivity from [beta-32P]TDP and [gamma-32P]ATP in TTP suggests that these two compounds are its precursors. Furthermore, TTP synthesis was inhibited by ADP and relatively low concentrations of Zn2+. These results suggest that TTP synthesis is catalyzed by an ATP:TDP transphosphorylase rather than by the cytoplasmic adenylate kinase that may be present in the vesicles. After osmotic lysis of the vesicles at alkaline pH, TTP was recovered in protein-bound form. Concomitantly, a soluble thiamine triphosphatase, with alkaline pH optimum, was also released from the vesicles. No net synthesis could be obtained in the cytosolic fraction or in detergent-solubilized systems. Like TTP synthesis, chloride permeability of the vesicles was increased when the homogenate had been incubated with thiamine and particularly with TDP. Our results suggest a regulatory role of TTP on chloride permeability, but the target remains to be characterized.
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
Peeters, Maryline
Wins, Pierre
Schoffeniels, Ernest
Language :
English
Title :
Metabolism of Thiamine Triphosphate in Rat Brain: Correlation with Chloride Permeability
Publication date :
1993
Journal title :
Journal of Neurochemistry
ISSN :
0022-3042
eISSN :
1471-4159
Publisher :
Blackwell, Oxford, United Kingdom
Volume :
60
Issue :
2
Pages :
423-434
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
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