Abstract
Replicative intermediate (RI) is considered to be the double-stranded ribo-nucleic acid (RNA) template for synthesis of viral RNA, with bound nascent single-stranded viral RNA. A theoretical description of RI is based on the analysis of a steady state of biopolymerization on a template which determines not only nucleotide sequence, but also chain length. The hydrodynamic properties of RI isolated from Escherichia coli infected with bacteriophage R17 are compared with those of RNA isolated from R17 (single-stranded RNA) and of replicative form (RF) isolated from E. coli infected with R17. RF is double-stranded RNA template without any single-stranded component. Whereas S for R17 RNA is a function of the ionic strength (Gamma/2) of the solvent, S is almost invariant with Gamma/2 for RF. By contrast S for RI lies between the sedimentation constants for R17 RNA and RF and S varies with Gamma/2 as does R17 RNA. The weight distribution of S for RI demonstrates the heterogeneity of this material, and the variation in the weight distribution with ionic strength demonstrates the duality of structure in RI. Using S and [eta], the Mw for RI is estimated to be 2.6 x 10(6) daltons, as compared with the theoretical value of 2.9 x 10(6) daltons.