Table 3.

Peptidase nucleophile type is enriched according to gene expression profile.

Peptidase cluster	Asp	Cys	Met	Ser	Thr	Total peptidases
P1	0%	−6%	−1%	10%	–	95
P2	8%	−4%	−4%	6%	–	38
P3	–	−12%	−6%	22%	0%	55
P4	15%	3%	−8%	−4%	–	5
P5	−2%	−2%	8%	−14%	11%	80
P6	−1%	18%	−4%	−9%	−3%	51
P7	2%	9%	3%	−14%	1%	62
Total peptidases	19	66	108	172	21	386

The peptidase nucleophile content of each gene expression cluster (Figure 1) was calculated and compared to the frequency in the genome. The percentage difference observed and expected frequency is shown for the five most common nucleophiles: Asp, aspartate; Cys, cysteine; Met, methionine; Ser, serine; Thr, threonine.