Crystallization and preliminary X-ray analysis of an orthorhombic form of horse-spleen apoferritin.
Horse-spleen apofemtin crystallizes in two different space groups: cubic F432 and tetragonal P42(1)2 while its iron-containing analogue is known to present a cubic and an orthorhombic form. Up to now, only the structure of the cubic form has been fully investigated by X-ray diffraction, although some information concerning the molecular packing of the two other forms was deduced from analysis of X-ray photographs. While growing cubic crystals of horse-spleen apoferritin with Pt-mesoporphyrin IX, we obtained one crystal, with a diffraction limit of 2.4 A, belonging to the orthorhombic P2(1)2(1)2 space group, with unit-cell dimensions a = 181.6, b = 128.9, c = 128.9 A. The orientation of the non-crystallographic axes of the molecule was determined by self-rotation Patterson function and the structure was determined by the molecular-replacement method. The asymmetric unit consists of half an apoferritin molecule. Refinement of the structure is in progress, some preliminary results of the molecular packing are given.
Laboratoire de Cristallographie, ERS133 CNRS, Université Bordeaux, Talence, France.
B L
BL
d'Estaintot
A
A
Dautant
T
T
Granier
B
B
Gallois
M A
MA
Michaux
G
G
Précigoux