FIG. 7.

Vital stain of periplasmic proteins. The periplasmic fractions (each contained 200 μg of proteins) prepared from 6-h cultures were subjected to electrophoresis on an SDS-polyacrylamide gel (12.5%) containing herring sperm DNA (20 μg/ml) and then stained with Coomassie blue (left). A duplicate of the gel was renatured, stained with ethidium bromide, and visualized with UV light (right). Lanes: M, size markers; 1, YJ016; 2, SK005 (YJ016 Δvvn); 3, purified Vvn (a gift from C. M. Hsu; 0.1 mg); 4, DH5α(pUC19); 5, DH5α(pSI014). pSI014 was a pUC19 derivative containing the intact vvn gene. The position of Vvn is indicated by an arrowhead. A minor band detected in the purified Vvn by vital stain could be a degraded product of this nuclease.