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. 2012 Oct 9;2:717. doi: 10.1038/srep00717

Table 4. Comparison of amino acid residues involved in C-domain sACE interactions with Ang II and BPPb peptides and their structurally equivalent residues in the N-domain of sACE.

Ang II peptide BPPb peptide C-domain sACE specific RXPA380 inhibitor 17
C-domain sACE N-domain sACE C-domain sACE N-domain sACE C-domain sACE N-domain sACE
    K118a,b A94a,b    
    D121a,b T97a,b    
Q281 Q259 Q281 Q259 Q281 Q259
H353 H331     H353 H331
A354 A332     A354 A332
A356 A334 A356 A334 A356 A334
D358 D336        
    Y360b Y338b    
H383 H361     H383 H361
        E384c E362c
H387 H365     H387 H365
    E403a,b R381a,b    
        E411c E389c
K511 K489 K511 K489 K511 K489
H513 H491 H513 H491 H513 H491
    S516a,b N494a,b    
    S517a,b V495a,b    
Y520 Y498 Y520 Y498 Y520 Y498
Y523 Y501 Y523 Y501 Y523 Y523

The structurally equivalent residues in C-and N-domain of sACE were obtained by structural alignment of the two proteins in CLUSTALW. Remarkably, when the two structures are superimposed, the residues identified by sequence alignment superpose extremely well. All of the C-domain residues involved in Ang II binding are conserved in the N-domain. On the other hand, there are significant sequence differences in the N-domain sACE with those residues involved in C-domain binding to BPPb (a). The complete structure of BPPb bound to C-domain sACE allows the identification of additional binding sites not previously observed with domain specific inhibitor complex structures with C- and N-domains of sACE (b). Specific residues involved in C-domain sACE-RXPA380 binding but are not involved in interactions with the peptides (Ang II or BPPb) (c).