B V Vakil | PubMed Health

PubMed1989

A sensitive assay for Staphylococcus aureus nucleases.

A sensitive assay for staphylococcal nuclease involving incubation of the enzyme sample with heat-denatured [3H]thymidine labelled DNA from E. coli, precipitation with trichloroacetic acid and measurement of the radioactivity of acid-soluble nucleotides released has been developed. The assay is sensitive enough to be used for comparing the levels of nucleases elaborated by different strains of S. aureus as well as for determining the extent of contamination of S. aureus in food and water samples even at levels at which the conventional spectrophotometric and toluidine blue-DNA methods are totally inadequate.

Deoxyribonucleases↗

PubMed1984

Identification of a heat-labile cellular nuclease in Staphylococcus aureus with properties similar to the extracellular nuclease (EC 3.1.4.7).

Besides the well-known heat-stable extracellular staphylococcal nuclease (EC 3.1.4.7) and cell surface bound nuclease, one more nuclease, which is heat-labile, has been identified and purified on phosphorylated cellulose column and characterized. Analyses by Sephadex G-75 gel chromatography indicates that the heat-labile cellular nuclease has molecular weight of about 16,000 similar to those of extracellular and cell-surface bound nucleases. Like the heat-stable nucleases, the heat-labile enzyme acts on both DNA and RNA, is more active on heat-denatured DNA, requires Ca2+ ions for activity and maximum catalytic activity is observed at pH 9.8-10 and at 45 degrees C. The results suggest that the three enzymes have properties strikingly similar to one another and therefore may be related structurally.

Electrophoresis, Polyacrylamide Gel↗