title: The phospholipase A1 of Trypanosoma brucei does not release myristate from the variant surface glycoprotein.
abstract: [3H]Myristoyl-labeled variant surface glycoprotein (VSG) has been isolated from Trypanosoma brucei by reverse phase high performance liquid chromatography and used as substrate for the conversion by trypanosomal enzymes of membrane-form VSG to soluble VSG. Conversion is detected by the release of myristoyl-containing lipids. The major lipolytic enzyme of T. brucei, phospholipase A1, is effective for the hydrolysis of myristoyl esters of p-nitrophenol, in a colorimetric assay. However, the phospholipase is unable to cleave the myristoyl ester linkage of VSG. The phospholipase can be separated from the myristoyl-releasing activity of trypanosome homogenate by centrifugation, affinity chromatography, and anion-exchange chromatography. Elution profiles on anion-exchange high performance liquid chromatography also indicate that the phospholipase is inactive against VSG. A small amount of myristoyl-releasing activity associated with the purified phospholipase is probably due to contamination with a phosphodiesterase which releases myristoyl-containing diglyceride from VSG.
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000378:metabolism*; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism; D009596:Nitrophenols / Q000494:pharmacology; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054466:Phospholipases A1; D014346:Trypanosoma brucei brucei / Q000201:enzymology*; D014643:Variant Surface Glycoproteins, Trypanosoma
chemical_list: D006023:Glycoproteins; D009227:Myristic Acids; D009596:Nitrophenols; D014643:Variant Surface Glycoproteins, Trypanosoma; D019814:Myristic Acid; D010740:Phospholipases; D010741:Phospholipases A; D054466:Phospholipases A1; C024836:4-nitrophenol