Escherichia coli capsule bacteriophages. VIII. Fragments of bacteriophage 28-1

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Abstract
A host capsule depolymerase activity is associated with the particles of E. coli capsule bacteriophage 28-1. This is a large virus with a long, contractile tail terminating in a base plate with spikes. Isolated virions were exposed to a variety of dissociative reagents and conditions. They were then tested for residual infectivity and depolymerase activity, and inspected by electron microscopy. Very mild acid treatment (10-15 min at pH 4.0 and 37.degree. C) caused a specific detachment of some phage spikes and a moderate drop in infectivity and depolymerase activity. Large batches of viruses were fragmented in this manner and the detached spikes were isolated. The host capsule depolymerase activity was associated with these organelles. In negatively stained preparations, the spikes were .apprx. 18 nm long and .apprx. 5 nm thick. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they contained polypeptides with molecular weights of 80,000 and 145,000.