TY - JOUR
T1 - Rabbit myocardial cytosolic lysophospholipase
T2 - Purification, characterization, and competitive inhibition by L-palmitoyl carnitine
AU - Gross, R. W.
AU - Sobel, B. E.
PY - 1983
Y1 - 1983
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0020539228&partnerID=8YFLogxK
M3 - Article
C2 - 6833297
AN - SCOPUS:0020539228
SN - 0021-9258
VL - 258
SP - 5221
EP - 5226
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 8
ER -