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.
d'Estaintot
B L
BL
Laboratoire de Cristallographie, ERS133 CNRS, Université Bordeaux, Talence, France.
Dautant
A
A
Granier
T
T
Gallois
B
B
Michaux
M A
MA
Précigoux
G
G