Duplex circular monomers

C below the Tm of duplex AAV DNA. These duplex linear monomers did form duplex circular monomers and hnear dimers when exposed to annealing conditions. Thus, anneahng of intact linear AAV single polynucleotide chains led to the formation of two types of duplex linear monomers (1) those without cohesive single-stranded termini, and (2) those with cohesive single-stranded termini. 

Fig. 4. A model of the nucleotide sequence arrangement contained within AAV DNA, Two nucleotide sequence permutations are illustrated. Plus and minus strands may anneal to form duplex linear monomers with (3 and 4) or without cohesive 3 or 5 termini (1 and 2). Duplex linear monomers with cohesive termini can then form duplex circular monomers or duplex linear oligomers. In the figure the terminal repetitions are depicted as symmetrical nucleotide sequences. In the inset two alternative types of terminal repetitions are illustrated the first has the inverted repetition subterminal to the natural repetition, the second illustrates the possibility that a strand may have either an inverted or a natural terminal repetition...

Table 1. Exonucleolytic digestion of duplex AAV circular Monomers...

Figure 27-24 Structures of RecA protein spiral filaments. (A) RecA protein filament formed on circular duplex DNA in the presence of ATP(Y-S), shadowed with Pt and seen by electron microscopy. (B) Diagram of RecA bound to duplex DNA in the presence of ATP(y-S), as determined by electron microscopy. RecA monomers are shown as spheres, but their exact shape is unknown. (C) Diagram of RecA spiral filament in crystals of RecA protein free of DNA, based on X-ray crystallographic data. Arrows indicated alignment of monomers. From Howard-Flanders, West, and Stasiak.536...

The distinction between monomer, duplex, and triplex helices of DNA or RNA can be established by a comparison of absorption and circular dichroism (CD) spectroscopy. A clear difference in the CD is seen that distinguishes triplexes of RNA from those of DNA. The CD spectra... 

The base composition and sequence of a circular dimer (10 /un circular duplex) suggest that two monomeric units are attached to each other to form a new circular molecule. The monomeric genomes are fused in a dimer in a head-to-tail tandem fashion. The informational content of monomers and dimers has been shown to be essentially the same [the homolo is at least 90 (Clayton et al., 1970)]. This special form of mt DNA is predominantly found in cells in culture and in neoplastic tissues. The percentage of these oligomers apparently varies if the culture... 

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