Table 1. Accuracy of EC prediction by iCSA filter.

PSI-BLAST iteration	Swiss-Prot homologues identified by 482 queries	Swiss-Prot homologues with same EC as query	Total EC predictions using iCSA filter	Correct EC predictions using iCSA filter	Accuracy of EC prediction by iCSA filter, %
1	27,072	22,941	19,024	17,335	91.1
2	11,567	4,386	1,844	1,048	56.8
3	9,471	2,738	395	185	46.8
4	7,439	2,254	176	105	59.7
Overall	55,549	32,319	21,439	18,673	87.1

Results are shown for the iCSA prediction of EC number for Swiss-Prot homologues detected at each PSI-BLAST iteration, up to four, using 482 nonredundant CSA enzymes as queries. “Overall” figures use the results from all four interations in one calculation. EC predictions are deemed correct if they match to the third digit of the EC annotation in the Swiss-Prot database. Accuracy is calculated using the number of correct predictions divided by the number of predictions made. (Note that each Swiss-Prot may occur more than once because it may have been identified by separate queries. The totals include all predictions in order to provide an unbiased calculation of accuracy.)