Confusion of Four Major SCOP Classes at PA (Protein Abstract) Level:

 

Although all-Alpha folds usually have over 90% HL (total helix length as a ratio of total SSE length) attribute values, there are some exceptions. Similarly, although all-Beta folds usually have less than 20% HL values, there are some exceptions. These exceptional cases can cause confusions of all-Alpha folds with Alpha/Beta folds, and all-Beta folds with Alpha+Beta folds as shown in the following diagram. A similar observation can be also made on HN (no. of helixes as a ratio of total no. of SSEs) attribute values. (Data is not shown here.)