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S Tardivel

Publications and source records attributed to S Tardivel.

28 records · Page 2Linked to original sources
PubMed1990

Alkaline phosphatase from adult rat femur.

Four alkaline phosphatase forms from adult rat femur were distinguished on polyacrylamide gel electrophoresis: two soluble forms of Mr 165,000 and 110,000 in the water extract, and three membrane-bound forms of Mr 130,000, 110,000 and 100,000 extractable with deoxycholate. Alkaline phosphatase after SDS-treatment disintegrated into three kinds of monomers: of Mr 80,000, 65,000 and 50,000. The soluble fraction (extract I) contained subunits of Mr 80,000 and 55,000--whereas the pellet fraction (extract II), subunits of Mr 65,000 and 50,000. Since for native forms only three types of subunits were found it seems that, apart from homodimers, there are also some heterodimers composed of the Mr 65,000 and 50,000 subunits forming the native enzyme of Mr 110,000-115,000. Two denatured monomers: of Mr 80,000 and 50,000 may form two native homodimeric forms of Mr 165,000 and 100,000 while in the pellet two monomers: of Mr 65,000 and 50,000 may correspond to three native alkaline phosphatase forms: of Mr 130,000, 110,000-115,000 and 100,000. Probably the Mr 110,000-115,000 form is a heterodimer composed of subunits of Mr 65,000 and 50,000.

Alkaline Phosphatase↗
PubMed1990

Changes of femoral alkaline phosphatase activity in adult rats treated by sorbitol enriched or vitamin D3 deficient diet.

The effect of vitamin D3-deficiency and dietary sorbitol on serum calcium level, the activity and alkaline phosphatase (AP) pattern in femoral epiphysis were studied. Rats fed a diet supplemented with sorbitol or vitamin D3 showed the same serum calcium concentration and AP activity in serum and femur. Rats fed a vitamin D3-deficient diet displayed decreased serum calcium concentration and increased AP activity both in serum and femur. Four forms of AP were isolated from the femur of these rat groups: of Mr 100,000, 110,000, 130,000 and 165,000. Rats receiving the diet supplemented with sorbitol showed a marked rise in the activity of the Mr 165,000 form, and appearance of a new monomer of 100,000, never formed in two remaining groups.

Alkaline Phosphatase↗
PubMed1988

Homodimer and heterodimer forms of adult rat intestinal alkaline phosphatase.

Three forms of alkaline phosphatase have been isolated from different sections of the small intestine: F3 180 kDa from the duodenum; F2 150 kDa principally jejunal; F1 120 kDa the only ileal form. Their catalytic properties have been compared as well as the electrophoretic properties the dimer and monomer of their phosphorylated intermediates. Pi was a competitive inhibitor of F1 and F3, whereas glycerophosphate was competitive inhibitor only of F3. Pi was a non competitive inhibitor of F2 and of a mixture F1 plus F3. Heating the phosphorylated enzyme preparations led to their dissociation into the phosphorylated monomers: F1 and F3 appear to be homodimers 65 kDa and 90 kDa peptides respectively whilst F2 seems to be a dimer formed from one of each monomer. F1 was phosphorylated faster but less intensively than F3. F2 was strongly phosphorylated over a long time-course and its 65 kDa monomer fraction was phosphorylated more strongly for longer than that from F1.

Alkaline Phosphatase↗
PubMed1988

[Effects of alkaline phosphatase inhibitors on intestinal transfer of calcium].

Adults rats receive by gavage 10 mM CaCl2 [+45Ca] solution containing or not 100 mM glucid, 10-100 mM EDTA or these both compounds. Calcium transfer is determined by the evaluation of [45Ca] in intestine and feces as well as in plasma and femur. Basic Ca++ transfer which corresponds to the CaCl2 solution was doubled in the presence of glucids. EDTA addition abolishes completely the glucid effect, exercising any influence on basic CA++ transfer. Injected into ligaturated ileal loop, the glucid gives the same effect. But the addition of phosphate not only removed glucid action but also inhibits the basic Ca++ transfer. The glucids, known acceptors of phosphate, increase Ca transfer. EDTA and phosphate, alkaline phosphatase inhibitors, exhibit an opposite effect. Phlorizin, as it was seen previously, acts exactly as EDTA. All these facts question: the simultaneous transfer of Ca and glucid, the possibility of a glucid phosphorylation, the part in these events of alkaline phosphatase, phosphorylating, phosphatasic and phosphorylable microvillar protein.

Alkaline Phosphatase↗
PubMed1988

[Differential phosphorylation of the 3 forms of alkaline phosphatase of the small intestine of adult rats].

Semi-purified preparations were obtained from duodenal, jejunal or ileal mucosa containing one of the three alkaline phosphatase forms. The Mr of the isoenzymes were for F1 120, F2 150, F3 180 kDa. F1 was the only species found in the ileum; F2 was duodenal but mainly jejunal; F3 was found mainly in duodenum. These enzymes forms were the only phosphorylable proteins in these preparations. Following treatment with denaturing agents they were separated on gel electrophoresis into monomers F': F'1 65, F'2 65 and 90, F'3 90 kDa. Thus F2 could be an heterodimer. All were far more phosphorylated from ATP than from inorganic phosphate. As compared with F1, F3 was relatively more sensitive to ATP and less sensitive to inorganic phosphate.

Alkaline Phosphatase↗
PubMed1987

Phosphorylable proteins and alkaline phosphatase of brush border membranes from different parts of the rat small intestine.

1. The distribution along the small intestine of phosphorylable proteins from the brush border has been studied by gel electrophoresis. 2. Four proteins, with apparent Mr of 190, 160, 140 and 120 kDa were distributed unequally along the gut, which incorporated 32P from gamma 32P (ATP) to different degrees. 3. Alkaline phosphatase activity has been shown to follow the same distribution. 4. Under denaturing conditions 90, 85 and 65 kDa proteins were observed, whilst the proteins of 190, 160, 140 and 120 kDa had disappeared. 5. All these proteins, with the exception of the 190 kDa protein, had also been labelled with 32Pi. Furthermore, a difference in the phosphorylation of the 65 kDa and the 90-85 kDa proteins was observed. 6. The 65 kDa protein like commercial calf alkaline phosphatase had a ratio of phosphorylation from ATP to phosphorylation from Pi less than the 90 and 85 kDa proteins. 7. Mg2+ (2.5-10 mM) decreased phosphorylation of only the 65 kDa protein whilst beta-glycerophosphate inhibited phosphorylation of all forms of alkaline phosphatase. 8. Incorporation of gamma 32P (ATP) into the proteins was enhanced in the presence of 5 mM theophylline or EDTA. 9. The nature of the phosphorylation of these different proteins is discussed.

Adenosine Triphosphate↗
PubMed1987

[Action of bivalent cations on the alkaline phosphatase activity of intestinal microvilli. Influence of pH and substrate].

At alkaline or neutral pH and with PNPP or ATP as substrates, the effect of cations on alkaline phosphatase of jejunal microvilli was shown to differ, i.e. Mg++ had an activating effect at high concentrations, Zn++ slightly inhibiting, Ca++ and Co++ were inactive at all concentrations. At neutral pH with PNPP as a substrate, Mg++ and Co++ were active, Ca++ inactive and Zn++ slightly inhibiting at high concentrations. Using ATP as a substrate, all four cations were activators at all concentrations studied (0.2 to 5 mM). In the latter physiological conditions (pH and substrate), similar effects of the cations were observed with microvilli from other segments of rat small intestine.

Adenosine Triphosphate↗
PubMed1980

[Relations between the phosphorylation of aminated molecules and their action on the absorption of calcium].

Various amino acids and guanidines (L-lysine, L-aspartic and L-glutamic acids, creatine, taurocyamine and glycocyamine), studied in ileal ligated loops, increased intestinal calcium absorption in the rat. L-arginine was effective per os. Since these compounds are highly phosphorylable, a phosphorylation mechanism may be involved in the stimulation of calcium absorption. The phosphorylated derivative of creatine was detected in the ileal mucosa of rats receiving creatine in the ileal ligated loop. Modified amino acids, such as 5-methyl-L-glutamate, asparagine or glutamine, whose phosphorylable function was masked by a methyl or an amide radical, were not effective in enhancing calcium absorption. Assays in vitro showed that an ileal mucosa extract phosphorylated arginine, lysine, glycocyamine and taurocyamine in the presence of ATP, acting as a phosphate donor.

Adenosine Triphosphate↗
PubMed1979

[Effect of creatine and other phosphorylable amino compounds on the ileal absorption of Ca-45 in the rat].

Some carbohydrates which increase calcium absorption were phosphate acceptors. When administrated to adult Rat in ileal ligated loop, phosphorylable amino compounds such as creatine, L-aspartic and L-glutamic acids also increased calcium absorption; other effective compounds such as D- and L-lysine and D-alanine might be involved in reactions of phorphorylation. L-alanine, L- and D-valine and asparagine were ineffective in enhancing calcium absorption and were not phosphorylable. Injection of creatine into ileal loop induced the formation of its phosphorylated derivative. Absorption of the amino compound was not correlated with the fact that they were effective on calcium absorption.

Amino Acids↗