4BX7

trans-divalent streptavidin bound to biotin-4-fluorescein

Entity

Entity ID	Chain ID	Description	Type	Chain length	Formula weight	Number of molecules	DB Name (Accession)	Biological source	Descriptive keywords
1	A	STREPTAVIDIN	polymer	128	13321.4	1	UniProt (P22629) Pfam (PF01382) In PDB	STREPTOMYCES AVIDINII
2	B	STREPTAVIDIN	polymer	133	14056.0	1	UniProt (P22629) Pfam (PF01382) In PDB	STREPTOMYCES AVIDINII
3	A	(4S)-2-METHYL-2,4-PENTANEDIOL	non-polymer		118.2	1	Chemie (MPD)
4	B	biotin-4-fluorescein	non-polymer		644.7	1	Chemie (B4F)
5		water	water		18.0	78	Chemie (HOH)

Sequence modifications

A: 13 - 139 (UniProt: P22629)

PDB	External Database	Details
Ala 140	-	expression tag
Ala 23	Asn 47	engineered mutation
Asp 27	Ser 51	engineered mutation
Ala 45	Ser 69	engineered mutation

B: 13 - 139 (UniProt: P22629)

PDB	External Database	Details
Glu 140	-	expression tag
Glu 141	-	expression tag
Glu 142	-	expression tag
Glu 143	-	expression tag
Glu 144	-	expression tag
Glu 145	-	expression tag

Contents of the asymmetric unit

Polymers	Number of chains	2
	Total formula weight	27377.4
Non-Polymers*	Number of molecules	2
	Total formula weight	762.9
All*	Total formula weight	28140.3

*Water molecules are not included.