Effect of Pyrimidine Bases

Comparing matrix elements of simple models of two purine nucleobases with those calculated for WCP dimers (Table 3), one wonders about the effect of pyrimidine nucleobases on the electronic coupling matrix elements of hole transfer in DNA [14, 73]. 

Detailed analysis [74] of the pertinent molecular orbitals shows that it is impossible to identify any orbital-based direct involvement of the pyrimidine nucleobases in the hole transfer (see Fig. 2). Therefore, hole transfer always proceeds via purine bases, irrespective of whether they are arranged in the same or in opposite strands. However, the electronic coupling is notably 

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