Table 3. Occurrences of the Hydrogen Bonds Formed between the Q38 Side Chain Amide (NE2) and the 3′T(O2) or 5′T(O2) of the TTD/TT Motif in the MD Trajectories for the WT and Mutant Pol η Systems.

	occurrencea
	TTD		TT
	3′Tb	5′T	3′T	5′T
WT	0.47	0.19	0.46	0.00
R61K	0.29	0.04	0.14	0.71
R61A	0.47	0.09	0.31	0.00
S62L	0.35	0.13	0.79	0.00
S62A	0.54	0.47	0.56	0.97

^aThe occurrence is defined as the fraction of saved configurations exhibiting this specific hydrogen bond, where a hydrogen bond is defined to have a heavy-atom donor–acceptor distance less than 3.5 Å and a donor–hydrogen–acceptor angle of 145–180°. Some of the hydrogen bonds listed for the 3′ and 5′ thymines are bifurcated and therefore are reported in both the 3′T and 5′T columns.

^bThe hydrogen bond to 3′T(O2) is depicted in Figure 4.