1W21

Structure of Neuraminidase from English duck subtype N6 complexed with 30 mM sialic acid (NANA, Neu5Ac), crystal soaked for 43 hours at 291 K.

Entity

Entity ID	Chain ID	Description	Type	Chain length	Formula weight	Number of molecules	DB Name (Accession)	Biological source	Descriptive keywords
1	A, B, C, D	NEURAMINIDASE	polymer	389	43011.5	4	UniProt (Q6XV27) Pfam (PF00064) In PDB	INFLUENZA A VIRUS
2	E, F, H	2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose	branched		424.4	3	In PDB GlyTouCan (G42666HT)
3	G	alpha-D-mannopyranose-(1-6)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose	branched		545.5	1	In PDB GlyTouCan (G41734DZ)
4	C, A, D, B	N-acetyl-alpha-neuraminic acid	non-polymer		309.3	8	Chemie (SIA)
5	C, A, D, B	GLYCEROL	non-polymer		92.1	4	Chemie (GOL)
6	C, A, D, B	2-acetamido-2-deoxy-beta-D-glucopyranose	non-polymer		221.2	5	Chemie (NAG)
7	C, A, B	beta-D-mannopyranose	non-polymer		180.2	3	Chemie (BMA)
8	C, A, B	alpha-D-mannopyranose	non-polymer		180.2	10	Chemie (MAN)
9	B, C, D, A	CALCIUM ION	non-polymer		40.1	4	Chemie (CA)
10		water	water		18.0	1723	Chemie (HOH)

Contents of the asymmetric unit

Polymers	Number of chains	4
	Total formula weight	172046.1
Branched	Number of molecules	4
	Total formula weight	1818.7
Non-Polymers*	Number of molecules	34
	Total formula weight	6450.9
All*	Total formula weight	180315.7

*Water molecules are not included.