Human DPD domain (%) Pig DPD sequence homology 93.2 92.9 94.5 88.2 Secondary structure prediction program I II/III IV V YASPIN 71.4 74.6 77.1 75.8 PSIPHRED 70.1 74.9 72.5 88.0

Table 2: The alignment scores between the predicted secondary structure of human DPD and the pig DPD crystal structure. The secondary structure prediction programs, YASPIN and PSIPRED, were used to predict the secondary structures of each human DPD domain and compared with the secondary structure taken from the pig DPD crystallographic analysis [9] using the Clustal W program.