| 摘要 |
<p>- Extracellular neuraminidase (NANAase) is produced by the microorganism Arthrobacter sialophilum sp. nov. The enzyme is included from this microorganism by a variety of glycoproteins. The preferred enzyme inducer is a hot water extract of edible bird s nest which has been mildly acidtreated. The microorganisms, after aerobic growth in complete medium of relatively simple composition, are harvested, washed, salt-shocked, and induced in mineral salts solution which leads to facile enzyme induction. The produced NANAase is purified by ammonium sulfate fractionation, DEAE cellulose chromatography, gel filtration and ultrafiltration. The enzyme can further be readily crystallized from concentrated solutions. Disc gel electrophoresis at both acidic and basic pH's showed a major protein band. The predominant protein contained NANAase activity. The NANAase has an apparent molecular weight of 87,000 daltons. The purified enzyme has a pH optimum of 5-6, an apparent Km of 2.08 mg/ml for Collocalia mucoid and 3.3 x 10-3 M for N-acetylneuraminlactose and is insensitive to Ca++ ions and EDTA. Linkage specificity studies using N-acetylneuraminlactose and colominic acid indicated that the NANAase hydrolyzes (.alpha., 2-3), (.alpha., 2-6) or (.alpha., 2-8) linkages. The above-identified microorganism produces about 5 mg of NANAase/liter of induction medium and is an excellent source for the preparation of relatively large quantities of homogeneous NANAase.</p> |
