Krishnakumari Shanmuga Sundaram

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D- and L-cycloserine were shown to be irreversible inhibitors of the first enzyme of the sphingolipid pathway, 3-ketodihydrosphingosine synthetase, in a study using bacterial and brain microsomal enzymes. L-Cycloserine was shown to be 100 times more inhibitory than the D-isomer for the brain microsomal enzyme in vitro. In vivo, L-cycloserine caused a 70%(More)
Subcutaneous injection of L-cycloserine resulted in a 28% reduction in cerebroside levels in mouse brain but had no effect on the levels of gangliosides. In contrast, intraperitoneal injection results in a reduction of ganglioside as well as cerebroside + sulfatide levels. The route of injection influenced the degree of 3-ketodihydrosphingosine synthase(More)
Galactosylceramide sulfotransferase (EC 2.8.2.11) catalyzes the biosynthesis of sulfatide from galactocerebroside and adenosine 3'-phosphate 5'-phosphosulfate (PAPS). This enzyme is developmentally controlled, reaching a maximum activity in the brains of mice corresponding to that of maximum myelination. The product, sulfatide, is an important component of(More)
The modulation of phosphosphingolipid synthesis by vitamin K depletion has been observed in the vitamin K-dependent microorganism, Bacteriodes levii. When cultured briefly without the vitamin, a reduction occurred in the activity of the first enzyme of the sphingolipid pathway, 3-ketodihydrosphingosine synthase. In this report, 16-day-old mice were treated(More)
L-cycloserine was found to significantly inhibit the activity of the first enzyme of the sphingolipid pathway when added to growing cultures of Bacteroides levii. The effect of cycloserine on the synthesis of the sphingolipids showed that ceramidephosphorylethanolamine was inhibited to a greater degree than ceramidephosphorylglycerol, although synthesis of(More)
OBJECTIVE To elucidate free radical scavenging activity of ethanolic extract Lagenaria siceraria (L. siceraria) (Molina) fruit. METHODS The free radical scavenging activity of the L. siceraria (Molina) fruit extract was assayed by using α,α-diphenyl-β-picrylhydrazyl (DPPH), 2,20-azinobis 3-ethyl benzothiazoline-6-sulfonate (ABTS), FRAP, reducing power,(More)
We have shown previously that the administration of warfarin to 16-day-old mice results in a significant reduction in levels of sulfatides, and to a lesser degree a reduction of other sphingolipids in brain. Vitamin K stimulates biosynthesis of sulfatides in warfarin-treated mice. We now report that warfarin inhibits brain sulfotransferase activity. This(More)
The established role of vitamin K in nutrition is as a cofactor in the post-translational conversion of specific glutamyl to gamma-carboxyglutamyl (Gla) residues in a limited number of proteins. Administration of the vitamin K antagonist warfarin has previously been shown to decrease brain sulfatide concentrations and decrease brain galactocerebroside(More)
Previous work has shown that vitamin K regulates brain sulfotransferase activity. We now show that activity is lost after treatment with acid phosphatase and is restored with ATP. Orthophosphate activates sulfotransferase to a small degree (26%) with a maximum at 3 mM. Vitamin K1 (or menadione) + orthophosphate stimulates activity 400%; vitamin K alone is(More)