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Hydrolysis of sphingomyelin and phosphatidylcholine by midgut homogenates of the stable fly
Author(s) -
Spates George E.,
Bull Don L.,
Chen Andrew C.
Publication year - 1990
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.940140102
Subject(s) - sphingomyelin , phosphatidylcholine , hydrolysis , biochemistry , substrate (aquarium) , stable fly , enzyme , biology , phospholipase , phosphorylcholine , lecithin , chromatography , phospholipid , chemistry , stomoxys , cholesterol , membrane , muscidae , ecology
Qualitative and quantitative analyses were made to characterize the enzymatic degradation of sphingomyelin and phosphatidylcholine by midgut homogenates of the adult stable fly, Stomoxys calcitrans (L.). The results indicated that sphingomyelin was hydrolyzed by an enzyme with sphingomyelinase‐like properties, and that phosphatidylcholine was hydrolyzed by an enzyme with properties similar to phospholipase C. The optimum pH for the sphingomyelinase was 7.6, and the rate of hydrolysis of sphingomyelin at that pH was linear from 1 to 4 nmol of substrate and 5 to 25 μg of enzyme preparation. Dialysis of the homogenates against Tris‐HCI and imidazole buffers resulted in a decrease of sphingomyelinase activity by 59% and 98%, respectively, and the original activity was not restored with the addition of Ca ++ , Mg ++ , or Mn ++ .