Distribution^{1}

Average

Std. Dev.

Number residues

tvalue^{2}

pvalue

Percent overlap^{3}


Catalytic

0.19

0.03

844







Buried

0.18

0.05

6,310

2.0

1.5E21

84.9

Intermediate

0.16

0.05

5,818

2.0

5.6E58

70.4

Exposed

0.15

0.05

6,000

2.0

1.2E101

58.7

 ^{1} Accessibility is coarsegrained into three levels, which roughly correspond to the third most buried, middle third and third least buried (exposed) residues. ^{2} Comparison of each accessibilityfiltered PDF to the catalytic PDF; tvalue and pvalues are from a twosample Ttest comparing each of the accessibility PDFs to the catalytic residue PDF. ^{3} Percent overlap compares each accessibility level distribution to the catalytic residue distribution, which is calculated over the histogram of sampled data.