标题：Biochemical Characterization of 60S Acidic Ribosomal P Proteins from Porcine Liver and the Inhibition of Their Immunocomplex Formation with Sera from Systemic Lupus Erythematosus (SLE) Patients by Glycyrrhizin in Vitro
摘要：The three casein kinase II (CK-II) phosphate acceptors (p35, p17 and p15) in the Superdex CK-II fraction prepared from a 1.5 M NaCl extract of porcine liver were selectively purified by glycyrrhizin (GL)-affinity column chromatography (HPLC) as a heterocomplex associated with CK-II. Determination of the N-terminal amino acid sequences and immunological tests confirmed that these three CK-II phosphate acceptors belong to the family of 60S acidic ribosomal proteins (P0, P1 and P2). Three polyphenol-containing anti-oxidant compounds [catechin, epigallocatechin gallate (EGCG) and quercetin] inhibited CK-II activity (phosphorylation of these ribosomal P proteins) in a dose-dependent manner in vitro. Quercetin (ID50n=approx. 50 nM) was found to be an effective CK-II inhibitor. In contrast, CK-II activity was significantly stimulated by lower doses (0.3-3 μM) of GL, but was inhibited at high doses above 30 μM. As expected, GL at high doses above 200 μM inhibited the immunocomplex formation of 60S acidic ribosomal P proteins with their specific antibodies in the sera from patients with systemic lupus erythematosus (SLE). These results suggest that (i) a GL-affinity column is useful for effective purification of 60S acidic ribosomal P proteins from various mammalian cells as a heterocomplex associated with CK-II; and (ii) a relative high dose of GL may prevent the immunocomplex formation of 60S acidic ribosomal P proteins with their specific antibodies in the sera of SLE patients.
关键词：60S acidic ribosomal P protein;casein kinase II;casein kinase II inhibitor;glycyrrhizin;glycyrrhizin-binding protein;anti-oxidant compound
