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Your search keyword '"Head, M. R."' showing total 37 results
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37 results on '"Head, M. R."'

2. Evolution of the IBM Cloud: Enabling an enterprise cloud services ecosystem

Author

Kochut, A., primary, Deng, Y., additional, Head, M. R., additional, Munson, J., additional, Sailer, A., additional, Shaikh, H., additional, Tang, C., additional, Amies, A., additional, Beaton, M., additional, Geiss, D., additional, Herman, D., additional, Macho, H., additional, Pappe, S., additional, Peddle, S., additional, Rendahl, R., additional, Tomala Reyes, A. E., additional, Sluiman, H., additional, Snitzer, B., additional, Volin, T., additional, and Wagner, H., additional

Published
2011
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3. Tb3+ binding to Ca2+ and Mg2+ binding sites on sarcoplasmic reticulum ATPase.

Author

Highsmith, S R and Head, M R

Abstract

The interactions of Tb3+ and sarcoplasmic reticulum (SR) were investigated by inhibition of Ca2+-activated ATPase activity and enhancement of Tb3+ fluorescence. Ca2+ protected against Tb3+ inhibition of SR ATPase activity. The apparent association constant for Ca2+, determined from the protection, was about 6 x 10(6) M-1, suggesting that Tb3+ inhibits the ATPase activity by binding to the high affinity Ca2+ binding sites. Mg2+ did not protect in the 2-20 mM range. The association constant for Tb3+ binding to this Ca2+ site was estimated to be about 1 x 10(9) M-1. No cooperativity was observed for Tb3+ binding. No enhancement of Tb3+ fluorescence was detected. A second group of binding sites, with weaker affinity for Tb3+, was observed by monitoring the enhancement of Tb3+ fluorescence (lambda ex 285 nm, lambda em 545 nm). The fluorescence intensity increased 950-fold due to binding. Ca2+ did not complete for binding at these sites, but Mg2+ did. The association constant for Mg2+ binding was 94 M-1, suggesting that this may be the site that catalyzes phosphorylation of the ATPase by inorganic phosphate. For vesicles, Tb3+ binding to these Mg2+ sites was best described as binding to two classes of binding sites with negative cooperativity. If the SR ATPase was solubilized in the nonionic detergent C12E9 (dodecyl nonaoxyethylene ether alcohol), in the absence of Ca2+, only one class of Tb3+ binding sites was observed. The total number of sites appeared to remain constant. If Ca2+ was included in the solubilization step, Tb3+ binding to these Mg2+ binding sites displayed positive cooperativity (Hill coefficient, 2.1). In all cases, the apparent association constant for Tb3+, in the presence of 5 mM MgCl2, was in the range of 1-5 x 10(4) M-1.

Published
1983
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37. Pancreatobiliary and biliary control of fecal beta-glucuronidase activity in the rat.

Author

Head MR, Fukumoto HE, and Chang GW

Subjects
Animals, Bile Ducts surgery, Body Weight, Ligation, Male, Rats, Rats, Inbred Strains, Bile physiology, Feces enzymology, Glucuronidase analysis, Pancreatic Juice physiology
Abstract

Bile duct ligation experiments suggest that bile is an important regulator of intestinal beta-glucuronidase, an enzyme thought to be involved in colon carcinogenesis. Exclusion of pancreatobiliary secretions from the rat intestine significantly decreases glucuronidase activity (Roberton et al., Cancer Res., 42 (1982) 5165-5166). However, the separate roles of pancreatic and biliary secretions have not been examined. We ligated the bile ducts of rats at the hepatic duct, allowing pancreatic juice but not bile to enter the intestine, or at the Sphincter of Oddi, excluding pancreatic juice as well as bile. Fecal beta-glucuronidase activity was lowered in both cases, indicating that bile itself, and not pancreatic juice, is a major factor modulating beta-glucuronidase activity.

Published
1988
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