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Phosphocholine phosphatase and alkaline phosphatase are different enzymes in hamster heart
Author(s) -
Hatch Grant M.,
Choy Patrick C.
Publication year - 1987
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02533949
Subject(s) - phosphocholine , phosphatase , choline , alkaline phosphatase , biochemistry , hamster , phosphatidylcholine , chemistry , enzyme , acid phosphatase , choline kinase , phosphomonoesters , phosphorylcholine , biology , phospholipid , microbiology and biotechnology , membrane , inorganic phosphate
The CDP‐choline pathway is the major pathway for the synthesis of phosphatidylcholine in the hamster heart. The formation of phosphocholine from choline was regarded as the first committed reaction in this pathway. We demonstrated earlier that the phosphocholine pool in the heart was substantially less than that found in other tissues, and we observed that a substantial amount of the phosphocholine was hydrolyzed back to choline by a phosphatase. This phosphatase was located in the microsomal fraction of the heart, and unlike alkaline phosphatase, it was not inhibited by amino acids. The pH optima and heat sensitivity of phosphocholine phosphatase were also found to differ from alkaline phosphatase. Phosphocholine did not inhibit the hydrolysis of p‐nitrophenylphosphate, but a “mixed type” inhibition of the hydrolysis of phosphocholine was observed in the presence of pnitrophenylphosphate. Our data support the hypothesis that these two activities originate from separate and distinct enzymes, and we postulate that the cardiac phosphocholine phosphatase may play a role in the regulation of the phosphocholine pool size in the hamster heart.