CRYSTALLIZATION OF BIOSYNTHETIC ARGININE DECARBOXYLASE FROM ESCHERICHIA-COLI

Putrescine is die immediate precursor for the synthesis of polyamines and is normally generated by the action of ornithine decarboxylase. Ho wever, putrescine can also be produced by die conversion of arginine t o agmatine by arginine decarboxylase (bADC) followed by the release of urea by agmatine ureohydrolase. Aminoacid sequence homology with die eukaryotic ornithine decarboxylases suggests that bADC may be a model for this group of decarboxylases. We report here die crystallization o f arginine decarboxylase from E. coli. Crystals up to 1 mm in size are grown by vapor equilibration using Li2SO4 and polyethylene glycols as precipitants. The crystals exhibit diffraction maxima beyond 3 angstr om resolution and belong to space group P4(1(3))2(1)2 with a = 192.4 a nd c = 121.0 angstrom. These unit-cell dimensions together with the es timated density of die crystals suggest the presence of one tetramer o f bADC (71 kDa subunit-1) per asymmetric unit (V(m) = 2.0 angstrom3 Da -1).