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Results for “Calcium Isotopes”

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At least 433 records · Page 24Linked to original sources
PubMed1982

Characterization of the Ca2+ binding sites of calmodulin from bovine testis using 43Ca and 113Cd NMR.

The exchange rates of Ca2+ ions to the two classes of sites on calmodulin have been determined from the temperature dependence of the 43Ca NMR line width. The exchange rates were found to differ by a factor of about 40 at room temperature. The apparent pK value for one of these classes was estimated from the pH dependence of the 43Ca line width. The pK values of the two-high-affinity sites were found to differ about 0.1-1. Zn2+ ions were shown to bind to calmodulin and affect the exchange rates of Ca2+ and Cd2+ for all four sites.

Animals↗
PubMed1982

Origins of neutral sterols in human feces studied by stable isotope labeling (D and 13C). Effect of phytosterols and calcium.

A stable isotope labeling (13C and D) was administered to 8 subjects in order to observe the short-term effect of phytosterols (Cytellin 9 g/day) or calcium (calcium gluconate 3 g/day) on the processes involved in cholesterol elimination in the feces. Under control conditions, the mean fraction of fecal cholesterol having a plasmatic origin was 69% and that of cholesterol secreted by the digestive tract 11%. The remaining fraction represented unabsorbed dietary cholesterol. While both treatments reduced the absorption of cholesterol, Cytellin enhanced the fecal excretion of plasma cholesterol and calcium lowered it. The change observed in the rate of intestinal external secretion did not follow the change in the fecal excretion of cholesterol.

Adult↗