Linear bacteriophage DNAs

The non-linear dependence of the relaxation process on the DNA concentration was also observed in stopped-flow experiments and the same mechanism, i.e. fast pre-equilibrium followed by a slow intercalation step, was proposed." This latter study did not report values for the individual rate constants. The mechanism proposed in Scheme 4 was employed in subsequent studies despite the criticism on the accuracy for the data related to the fast kinetic component (see below). The original temperature jump study also showed that the relaxation kinetics depend on the structure of the DNA.117 The slower intercalation rate for 5 with T2 Bacteriophage DNA when compared to ct-DNA was ascribed to the glucosylation of the former DNA (Table 3). 

The T-odd bacteriophages Tl, T3, T5, and T7 are medium-sized phage with linear duplex DNA genomes. Replication of linear DNA in these and in many other genomes presents a problem. Even if the RNA primer segment is made at the very 3 end of the template strand, there will be a gap in the final replicated strand when the primer is digested out. Since there is no known enzyme that will add to the 3 end of a chain, this gap will remain unfilled. The problem is solved by terminal redundancy, the presence of a common 260-nucleotide... 

The cosmid is another variation of the plasmid and viral DNA vectors that has been developed to allow the cloning of DNA fragments that range from 40 to 50 kb. As the linear bacteriophage A DNA is... 

Note Results [83H1] of total intensity light scattering on linear T7 bacteriophage DNA (M=26.43-10 g-mol , from sequence analysis), analyzed according to Sharp and Bloomfield [68S1],... 

Bacteriophage lambda (X) is a good example for considering phage infection. In lytic infection, the injected linear double-stranded X DNA first circularizes. It is then transcribed to produce viral proteins needed for viral DNA replication and packaging as well as many molecules of viral capsid proteins. The viral DNA is replicated and the DNA copies are packaged into new phage... 

Figure 7.12 Quantitative analysis of labeled lambda bacteriophage PCR product plot of corrected peak area versus initial DNA template amount. Peak areas for the 500 bp lambda product were corrected for transit time through the detector and plotted as a function of the amount of DNA used in the PCR. A linear relationship is observed up to 250 pg DNA template. Inclusion of the high DNA template data points demonstrates PCR plateauing. (Reproduced with permission from KJ Ulfelder, Applications Information Bulletin A-1774, 1994. Copyright Beckman Instruments, Inc.)...

RNase protection assays (RPA) are based on the property of RNase to digest ii RNA, but not ds RNA, and its principles and applications resemble those of SI analysis (Lynn et al., 1983 Zinn et at, 1983) (Fig. 12.3). The sequence of interest is inserted in a plasmid downstream of a bacteriophage promoter (e.g., pUC118, pT7, etc.. Table 4.4). The purified plasmid is then restricted downstream of the inserted DNA and the linearized plasmid is transcribed in the presence of a labeled rNTP precursor. The transcript should be complementary to the RNA to be studied and an excess of probe is hybridized to its target. Any RNA remaining ss is then digested by one or more RNases. The size of the RNase-resistant probe and the... 

Bacteriophage X is a genetically complex and extensively studied virus of E. coli. Because it has been the object of molecular genetic research, it was investigated and developed as a vector. The DNA of phage X, in the form in which it is isolated from the phage particle, is a linear duplex molecule of about 45.5 kb pairs. The entire DNA sequence has been determined (SI). At each end are short, single-stranded 5 projections of 12 nucleotides that are complementary in sequence and by which the DNA adopts a circular structure when it is injected into the host cell i.e., X DNA naturally has cohesive termini that associate to form the cos site. 

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