Glycerophosphorylcholine phosphocholine phosphodiesterase activity of rat brain myelin.
Myelin isolated from rat brain possessed the ability to release phosphorylcholine from glycerophosphorylcholine, and this activity was enriched 3.2-fold over that of the original homogenate. This glycerophosphorylcholine phosphocholine phosphodiesterase activity had a pH optimum at 9.5, had a Km of 0.2 mM, and a Vmax of 150 nmoles/mg protein/hr. The enzyme had a specific requirement for Zn+2 with an optimum concentration at 0.25 mM. Maximum enzyme activity was at 50 degrees C and an Arrhenius plot showed a breakpoint at 40 degrees. p-Nitrophenylphosphorylcholine was also hydrolyzed by purified myelin and was a competitive inhibitor of glycerophosphorylcholine phosphocholine phosphodiesterase activity with a Ki of 0.075 mM. Glycerolphosphorylethanolamine was hydrolyzed only 5% compared with GPC, but it was not an inhibitor.
Kanfer
J N
JN
Department of Biochemistry, University of Manitoba, Winnipeg, Canada.
McCartney
D G
DG
D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002794:Choline; D005997:Glycerylphosphorylcholine / Q000378:metabolism*; D009186:Myelin Sheath / Q000201:enzymology* / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010767:Phosphorylcholine / Q000378:metabolism*; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity; D015032:Zinc / Q000494:pharmacology
D010767:Phosphorylcholine; D005997:Glycerylphosphorylcholine; D010727:Phosphoric Diester Hydrolases; D015032:Zinc; D002794:Choline; D002118:Calcium