. 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
		K118^a,b	A94^a,b
		D121^a,b	T97^a,b
Q281	Q259	Q281	Q259	Q281	Q259
H353	H331			H353	H331
A354	A332			A354	A332
A356	A334	A356	A334	A356	A334
D358	D336
		Y360^b	Y338^b
H383	H361			H383	H361
				E384^c	E362^c
H387	H365			H387	H365
		E403^a,b	R381^a,b
				E411^c	E389^c
K511	K489	K511	K489	K511	K489
H513	H491	H513	H491	H513	H491
		S516^a,b	N494^a,b
		S517^a,b	V495^a,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).