The Effect of 54 kD Calcium-binding Protein on the Platelet Membrane-bound PLA(2).
A 54 kD calcium-binding protein was isolated form porcine platelet after calcium precipitation and chromatography. Its calcium-blinding ability was proved by the Arasenzo III binding analysis. In order to study the physiology role of calcium-binding protein in platelets, an experiment to study the effect of 54 kD calcium-binding protein on the platelet membrane-bound PLA(2) was designed. We isolated porcine platelet membrane by the two-phases system and developed a simple assay method for phospholipase A(2) by the colorimetric micro-determination of long-chain fatty acid released by the enzyme. The results indicated that in the presence of 54 kD CaBP the activity of porcine platelet membrane-bound PLA(2) was stimulated with lower Ca(2+) concentration (<1 mM), but inhibited when the Ca(2+) concentration was above 1 mM. The inhibiting effect of 54 kD CaBP was not decreased with the increase of substrate concentration.
Wang
Tie-Lin
TL
Department of Biochemistry, School of Pharmacology, Shanghai Medical University, Shanghai 200032, China.
Fei
Zheng
Z
Zhuang
Qing-Qi
QQ