Jan 1, 1986

Characterization and localization of neutral sphingomyelinase in bovine adrenal medulla

Journal of Lipid Research
M Bartolf, R C Franson

Abstract

Homogenates of bovine adrenal medullae hydrolyzed exogenous sphingomyelin at 4.3 +/- 1.6 nmol X mg-1 X min-1 and 97% of this sphingomyelinase activity was sedimentable at 110,000 g. The sphingomyelinase had a broad pH optimum centered at pH 7. Enzymatic activity was maximal with 80 microM added Mn2+; Mg2+ supported less than half maximal activity and both Ca2+ and EDTA inhibited activity. No activity was detected in the absence of Triton X-100. Response to detergent was biphasic with dose-dependent stimulation from 0.02% to 0.05% Triton X-100 followed by inhibition with increasing concentrations of detergent. Activity in response to detergent was also modulated by protein concentration. Sphingomyelinase activity was associated with a plasma membrane-microsomal fraction. Phosphatidylcholine was not hydrolyzed under optimal conditions for sphingomyelin hydrolysis and a variety of other conditions. Neutral-active sphingomyelinase activity in adrenal medulla was similar in magnitude to that observed in other non-neural bovine tissues. This study demonstrates the presence of a potent neutral-active sphingomyelinase in a plasma membrane-microsomal fraction of bovine adrenal medulla. This enzyme may be involved in membrane fusion and ...Continue Reading

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Mentioned in this Paper

Pathologic Cytolysis
Establishment and Maintenance of Localization
Cations, Divalent
Catecholamine Secretion
Phosphoric diester hydrolase
Bos taurus
Sphingomyelin Phosphodiesterase 2
Phosphatidylcholines
Edetic Acid, Sodium Salt
Adrenal Glands

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