Structure of a purine nucleoside phosphorylase from Geobacillus stearothermophilus

The structure of His-tagged Geobacillus stearothermophilus purine nucleoside phosphorylase reveals a 'spanner in the works'.

MHHHHHHSSGLVPRGSGMKETAAAKFERQHMDSPDLGTGSENLYFQGAMMSVHIGAKAGEIAERILLPGDPLRAKYIAET
FLEGAVCYNEVRGMLGFTGTYKGERISVQGTGMGVPSISIYVNELIQSYGVKTLIRVGTCGAIQPDVRVRDVILAMSAST
DSNMNRLIFRGRDYAPTADFHLLRTAYEVGVEKGLALKVGNVFTADMFYNDEPNWETWARYGVLAVEMETAALYTLAAKF
GCRALSVLTVSDHILTGEETTAEERQMTFNEMIEVALEAAIRNGA

Magnesium chloride hexahydrate;
Calcium chloride dihydrate; Tris (base); BICINE pH 8.5; PEG 500* MME, PEG 20000