GL对PLA2

　　By means of heparin-affinity and glycyrrhizin （GL）-affinity column chromatographies （HPLC）， a GL-binding phospholipase A2 （gbPLA2） was selectively purified from the synovial fluids of patients with rheumatoid arthritis. This purified gbPLA2 was identified as a secretory type IIA PLA2 （sPLA2-IIA） since it was crossreacted with anti-sPLA2-IIA serum. The activity of purified sPLA2-IIA was inhibited by glycyrrhetinic acid （GA） and a GA derivative （oGA） in a dose-dependent manner， but it was more sensitive to GA than GL. Furthermore， it was found that （i） purified sPLA2-IIA is phosphorylated by casein kinase II （CK-II） in vitro； （ii） this phosphorylation induces in a significant stimulation of PLA2 activity； and （iii） oGA at one-tenth the concentration of GL inhibits the CK-II-mediated stimulation of sPLA2-IIA activity. These results show that （i） sPLA2-IIA is a GL-binding protein； and （ii） CK-II mediates stimulation of its PLA2 activity in vitro.