1SLF

APOSTREPTAVIDIN, PH 5.6, TWO MOLECULES OF (SO4)2 BOUND AT THE BIOTIN BINDING SITE

Entity

Entity ID	Chain ID	Description	Type	Chain length	Formula weight	Number of molecules	DB Name (Accession)	Biological source	Descriptive keywords
1	B, D	STREPTAVIDIN	polymer	135	14181.3	2	UniProt (P22629) Pfam (PF01382) In PDB	Streptomyces avidinii
2	B, D	SULFATE ION	non-polymer		96.1	4	Chemie (SO4)
3		water	water		18.0	180	Chemie (HOH)

Contents of the asymmetric unit

Polymers	Number of chains	2
	Total formula weight	28362.6
Non-Polymers*	Number of molecules	4
	Total formula weight	384.3
All*	Total formula weight	28746.9

*Water molecules are not included.