Table 1 Functional contribution of sectors defined for the ptRNase superfamily.

1

C26

Stabilizing the conformation (S-S bond with C84)

32

C40

Stabilizing the conformation (S-S bond with C95)

32

F46

Chain folding initiation site (CFIS) residue

33

C58

Stabilizing the conformation (S-S bond with C110)

32

S75

H-bonding with I106, Hydrophobic core

34

C84

Stabilizing the conformation (S-S bond with C84)

32

C95

Stabilizing the conformation (S-S bond with C40)

32

Y97

CFIS residue (fixes K41 through H-bonding)

12, 35

C110

Stabilizing the conformation (S-S bond with C58)

32

2

K7

P2 substrate binding site for endonuclease specificity

35

R10

P2 substrate binding site for endonuclease specificity

35

D14

H-bonding with Y25

36

Y25

Hydrophobic core, H-bonding with D14

36

M29

Hydrophobic core

37, 38

R33

H-bonding with R10 and M13

39

N34

Part of N-glycosylation sequence (N34-L35-T36)

40

T36

Part of N-glycosylation sequence(N34-L35-T36)

40

V47

Hydrophobic core

38

L51

Hydrophobic core

38

I106

Hydrophobic core, expedites folding

34

F120

Hydrophobic core, fixes the side-chain of H119

34

3

F8

Juxtaposing His12 by π-interaction with His12

35

Q11

P1 substrate binding site

35

H12

Catalytic triad residue (General base for catalysis)

34

M30

Hydrophobic core

38

K41

Catalytic triad residue (H-bond with transition state)

37

N44

H-bonding with H12 and K41

34

T45

Pyrimidine specificity of the B1 site

35

N71

B2 substrate binding site

35

A109

CFIS residue

35

P117

Trans-isomerization for folding

35

V118

CFIS residue

35

H119

Catalytic triad residue (General acid for catalysis)

34

D121

P1 substrate binding site

35