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Your search keyword '"Balasubramanian, Sathyamangalam V."' showing total 25 results
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25 results on '"Balasubramanian, Sathyamangalam V."'

4. Mechanism for the differential action of the N-linked carbohydrates

Author

Purohit, Sarla, Shao, Kui, Balasubramanian, Sathyamangalam V., and Bahl, Om P.

Subjects
Carbohydrates -- Analysis, Chorionic gonadotropin -- Analysis, Biological sciences, Chemistry
Abstract

Two carbohydrate mutants of human choriogonadotropin alpha lacking N-glycosyl chains at alpha52Asn and alpha78Asn were constructed. Circular dichroism of the two constructs revealed that the the absence of carbohydrate at the alpha52Asn resulted in conformational changes in the mutant causing the loss of signal transduction function. The function of alpha52Asn was the maintenance of the conformational integrity of the heterodimer rather than direct influence in the receptor binding.

Published
1997

5. Taxol-lipid interactions: taxol-dependent effects on the physical properties of model membranes

Author

Balasubramanian, Sathyamangalam V. and Straubinger, Robert M.

Subjects
Diterpenes -- Research, Liposomes -- Physiological aspects, Biological sciences, Chemistry
Abstract

Incorporation of taxol into liposomes results in the penetration of taxol in the acyl chain domain of the dipalmitoylphosphatidylcholine (DPPC) bilayer, which changes the physical properties of artificial and biological membranes. Studies of the conformation of taxol and its interaction with DPPC liposomes reveal that the conformation in DPPC membranes is similar to that in nonpolar solvents such as chloroform. The insertion of taxol into the bilayer disturbs the hydrocarbon chain formation, widening the DPPC phase transition.

Published
1994

24. <atl>Propofol, a general anesthetic, promotes the formation of fluid phase domains in model membranes

Author

Balasubramanian, Sathyamangalam V., Campbell, Robert B., and Straubinger, Robert M.

Subjects
*ANESTHETICS, *MEMBRANE lipids, *MEMBRANE proteins
Abstract

The molecular site of anesthetic action remains an area of intense research interest. It is not clear whether general anesthetics act through direct binding to proteins or by perturbing the membrane properties of excitable tissues. Several studies indicate that anesthetics affect the properties of either membrane lipids or proteins. However, gaps remain in our understanding of the molecular mechanism of anesthetic action. Recent developments in membrane biology have led to the concept of small-scale domain structures in lipid and lipid–protein coupled systems. The role of such domain structures in anesthetic action has not been studied in detail. In the present study, we investigated the effect of anesthetics on lipid domain structures in model membranes using the fluorescent spectral properties of Laurdan (6-dodecanoyl-2-dimethylamino naphthalene). Propofol, a general anesthetic, promoted the formation of fluid domains in model membranes of dipalmitoyl phosphatidyl choline (DPPC) or mixtures of lipids of varying acyl chains (DPPC:DMPC dimyristoyl phosphatidyl choline 1:1). The estimated size of these domains is 20–50 A˚. Based on these studies, we speculate that the mechanism of anesthetic action may involve effects on protein–lipid coupled systems through alterations in small-scale lipid domain structures. [Copyright &y& Elsevier]

Published
2002
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25. Effect of Pregnancy, Postnatal Growth, and Gender on Renal Sulfate Transport

Author

Lee, Hwa Jeong, Balasubramanian, Sathyamangalam V., and Morris, Marilyn E.

Abstract

Serum sulfate concentrations are increased in infants, young children, and pregnant women, compared with adult values. The objective of this investigation was to examine the influences of age, gender, and pregnancy on renal sulfate transport using guinea pigs as an animal model. Membrane vesicles were isolated from the kidney cortex of male animals at four different ages, from male and female adult animals, and from pregnant and nonpregnant female animals. There were no significant differences in marker enzymes for the brush-border membrane (BBM) or baso-lateral membrane (BLM) among all groups examined. Uptake was determined by a rapid filtration method and membrane fluidity by measuring the steady-state fluorescence anisotropy of 1,6-dipheny-1-3,5-hexatriene. The Vmaxvalues for Na+/sulfate co-transport in BBM were significantly increased with decreasing age, whereas the Kmfor this process was unchanged. The Vmaxand Kmfor Na+/sulfate co-transport in BBM of pregnant animals were significantly higher than the values in the nonpregnant group. Bicarbonate-driven anion exchange of sulfate in BLM was not different among the different age groups. The Vmaxfor the bicarbonate/sulfate exchange process in BLM was not different between pregnant and nonpregnant groups; however, the Kmfor this process in BLM of pregnant animals was significantly greater than the value in nonpregnant animals. There were no gender-related differences in sulfate transport in BBM or BLM isolated from adult male and female animals. Renal BBM fluidity was increased with decreasing age and in pregnant animals, suggesting that altered membrane fluidity may represent one possible mechanism to explain the increased sodium/sulfate uptake in young and pregnant animals. The higher Vmaxfor Na+/sulfate co-transport in young and pregnant animals suggests that there is an increased density of co-transporter protein or an increase in the rate of movement of the carrier protein (i.e., turnover) once loaded with sodium and sulfate. This increased conservation of inorganic sulfate in young and pregnant guinea pigs may be related to the increased demand for sulfated substrates, such as sulfated glycosaminoglycans, during growth and development.

Published
1999
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