Structure of Pyocin R

II. Subunits of Sheath

Abstract

1. The sheath of pyocin R was dissociated into subunits by treatment with 8M urea containing 0.1M Na₃PO₄, pH12.7, at 4°C for 2 days, or with 8M guanidine hydrochloride containing O.lM Na₃PO₄, pH8.4, at room temperature for 2 days, or with1% sodium dodecyl sulfate (SDS^***) containing 1% β-mercaptoethanol and O.OlM phosphate, pH7.0 at 96°C for 2min. Dissociation into subunits was examined by gel filtration through Bio-Glas 500, and polyacrylamide gel electrophoresis in the presence of SDS.
2. SDS polyacrylamide gel electrophoresis showed the presence of at least four structural components, one main and three minor components in the purified contracted sheath. The main component had a molecular weight of 35, 000 and the three minor components had those of 32, 000, 29, 000, and 26, 000. These four components differed from one another in amino acid composition. The subunit with a molecular weight of 29, 000 seemed to be a dimer of a smaller unit having a molec-ular weight of 14, 500.