Chains and heterogens:
PDB Chain Sequences:
>1r3fA (A:) msrprrrgrdingvllldkpqgmssndalqkvkriynanraghtgaldplatgmlpiclg eatkfsqylldsdkryrviarlgqrtdtsdadgqiveerpvtfsaeqlaaaldtfrgdie qipsmysalkyqgkklyeyarqgievprearpitvyellfirhegneleleihcskgtyi rtiiddlgeklgcgahviylrrlavskypvermvtlehlrelveqaeqqdipaaelldpl lmpmdspasdypvvnlpltssvyfkngnpvrtsgapleglvrvtegengkfigmgeidde grvaprrlvveypa
>1r3fA (A:) grdingvllldkpqgmssndalqkvkriynanraghtgaldplatgmlpiclgeatkfsq ylldsdkryrviarlgqrtdtsdadgqiveerpvtfsaeqlaaaldtfrgdieqipitvy ellfirhegneleleihcskgtyirtiiddlgeklgcgahviylrrlavskypvermvtl ehlrelveqaeqqdipaaelldpllmpmdspasdypvvnlpltssvyfkngnpvrtsgap leglvrvtegengkfigmgeiddegrvaprrlvveypa