[Purification and some properties of neuraminidase from the culture medium of Bacteroides loescheii ATCC 15930].

The purpose of this study is to investigate the mechanism on enhanced hemagglutination caused by neuraminidase from Bacteroides in an aspect of zeta-potential levels on erythrocytes and inhibitors on hemagglutination activity. The neuraminidase from the culture medium of Bacteroides loescheii ATCC 15930 was purified by ultrafiltration followed by DEAE-Sephacel anion exchange chromatography, fast protein, polypeptide, polynucleotide, liquid chromatography using Mono P column and finally high performance liquid chromatography using Shim-pack Diol-300 column. The purified enzyme appeared to be homogeneous by analytical polyacrylamide gel electrophoresis. The molecular weight was measured to be approximately 87,000 and the optimal pH was at 4.8. The isoelectric point was at 5.1. The enzyme showed relatively high specificity toward the linkage of NANA alpha (2----3) oligosaccharides and glycoproteins, and less toward the linkage of NANA alpha (2----6), and/or NANA alpha (2----8) oligosaccharides. When the human erythrocytes were treated by the purified enzyme, hemagglutination activities of some strains of Bacteroides gingivalis, Bacteroides denticola and Bacteroides intermedius were enhanced. Hemagglutination inhibition experiments using B. gingivalis 381 showed that the activity of hemagglutination was strongly inhibited by the arginine-containing peptides especially salmine derived from salmon, although the activity was unaffected by the sugars, amino acids and divalent cations such as Ca2+, Mn2+ and Mg2+. The zeta-potential level on asialo-erythrocytes treated by purified enzyme was considerably decreased compared to that of sialo-erythrocytes. It seems likely that the mechanism on hemagglutination by the B. gingivalis 381 may be involved in electrochemical affinity between the erythrocytes and bacterial cells with the reduction of zeta-potential, and in arginine-containing peptides as receptors of ligand-binding on erythrocytes.