68 Scopus citations


Rabbit myocardial lysophospholipase was purified 27,000-fold to near homogeneity by ammonium sulfate precipitation, DEAE-Sephacel, gel filtration, chromatofocusing, and hydroxylapatite chromatography. Chromatofocusing demonstrated two activity peaks, each with a molecular mass of 23,000 daltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both activity peaks had similar kinetic parameters (V(max) = 7 μol/mg/min, K(m) = 9-11 μM) and similar pH profiles (7.5 optimum). Each activity peak was competitively inhibited by L-palmitoylcarnitine with similar inhibitory constants (K(I) = 10-11 μM). In addition, palmitic acid competitively inhibited myocardial lysophospholipase (K(I) = 37 μM). A rapid loss of lysophospholipase activity resulted from heating at 37°C in the absence of substrate (t 1/2 = 3 min). This thermal denaturation was attenuated similarly by either lysophosphatidylcholine (15 μM) or L-palmitoylcarnitine (15 μM). Thus, L-palmitoylcarnitine complexes with purified myocardial lysophospholipase and competitively inhibits a major pathway of lysophosphatidylcholine catabolism, thereby potentially contributing to accumulation of lysophosphatides in ischemic myocardium and ventricular dysrhythmia.

Original languageEnglish
Pages (from-to)5221-5226
Number of pages6
JournalJournal of Biological Chemistry
Issue number8
StatePublished - 1983


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