Accessibility of the (14C)benzylpenicillin binding proteins in membranes of sporulating bacilli.

Triton X-100 treatment or freeze-thawing damages the membranes of sporulating or vegetative cells as seen by protein leakage from cells. A 40% increase in the specific [(14)C]benzylpenicillin-binding capacity of detergent-treated or frozen sporulating cells was observed. Neither freezing nor Triton X-100 treatment of vegetative cells produced a detectable effect on their [(14)C]benzylpenicillin-binding capacity. These data indicate the presence of penicillin-binding sites in intact sporulating bacilli not accessible to penicillin in routine binding assays. The chemical specificity of [(14)C]benzylpenicillin binding to detergent-treated sporulating cells is similar to that observed with untreated vegetative or sporulating cells.