The active sites of some polymerases are clearly flexible enough to accommodate major sugar modifications [19], [20].
On moderately transcribed genes, increased pausing would allow some polymerases to catch up to others.
For this to occur efficiently, high concentrations of pyrophosphate are required which may inhibit some polymerases.
Radical formation, inhibition of several enzymes like topoisomerase I and II, helicases and some polymerases were described for adriamycin [ 34- 36].
However, recent studies have discovered that some polymerases allow translesional but error prone replication across sites of DNA damage.
Alternatively, all promoters may initiate longer transcripts, and some polymerases stop at mTERF regardless of the promoter.
This possibility is supported by differences between the solution structure of a DNA LNA helix and the structure of double-stranded DNA [ 24] and that nucleotide incorporation opposite to an LNA base may be difficult for some polymerases [ 16].
Although some polymerases like yeast and human pol η can bypass 8-oxoG efficiently and accurately, other polymerases like yeast pol δ have been shown to stall at or just before the lesion, only by-passing about 14% of the time [ 59].
Consistent with the results of the previous section, extracts of cells with vector alone possess some DNA polymerase activity and all bands were consistent with accurate replication.
The yeast orthologue of Tim, Swi1, is required for stabilizing replication forks at some DNA polymerase pause sites, like those found at the mating type switch locus (Rts1) and centromeres, where replication terminates [11], [12], [57].
