| Popis: |
Properties of the Escherichia coli protoplast-infective agent (π) derived from T2 are compared with those of T2, as well as with the published properties of pneumococcus transforming principle (TP). π is somewhat more resistant to heat inactivation than T2, much less stable than TP. The destruction of π is a complex process characterized by at least three different reactions. Ultraviolet light inactivates π at a rate closely comparable to that observed for T2 and qualitatively similar to that for TP. The data indicate that the π mixture contains many damaged particles incapable of producing intact virus but capable of contributing to multiplicity reactivation. Unlike T2 and TP, π shows a remarkable instability in solutions of high osmolarity and in solutions containing surface-active agents. The pH stability of all three infective agents is roughly similar. Antiserum against T2 inactivates π, but at a slower rate and to a lesser extent than T2. Protein-inactivating reagents (especially those affecting sulfhydryl groups) have a greater effect on T2. On the other hand, agents primarily affecting DNA and presumed mutagens have parallel effects on T2, on π, and, qualitatively, on TP. DNAase and trypsin have no effect on T2 but destroy π rapidly. TP is destroyed more rapidly by DNAase, but is unaffected by trypsin. It is concluded that π is a highly organized structure consisting of other components in addition to DNA. In size and physical properties π is similar to a phage head, but its sensitivity to various reagents indicates that at least some of the physically protecting protein envelope is lacking or altered. More than one component of the π mixture may contribute to the infectivity for protoplasts; these components seem to differ markedly in their stability to various treatments. |
