X-ray diffraction data were measured by x-ray diffractometry to 5-A resolution for both the monoclinic form of @entity95 skeletal muscle aldolase (EC 4.1.2.13) and a @entity902 derivative. The heavy atom difference patterson was solved at 6-A resolution yielding eight distinct heavy atom sites. Choice was made of the enantiomorph and protein phases were calculated on the basis of single isomorphous replacement differences. The electron density map calculated from these phases was averaged according to the non-crystallographic molecular symmetry. Rotational symmetry analysis of native patterson and site symmetry analysis of refined heavy atom positions are consistent with the aldolase tetramer possessing a very high degree of 222 internal symmetry. The subunits in the tetramer are positioned in a tetrahedral configuration displaying a slight square @entity85 . Each subunit is roughly ellipsoidal in shape with the major @entity2270 nearly parallel to a local 2-fold @entity2270 . Prominent at the surface of each subunit were structural features resembling alpha helices. Each subunit contributes to its boundary surface at least six helices which are arranged in a barrel-like manner and possessing a right handed twist with respect to each other. Density associated with binding of substrate on the enzyme was located on the surface of each subunit. Cooperative aspects of the conformational changes produced upon substrate binding are discussed.

Structure of XXXX muscle aldolase at low resolution.

@entity2270 :: ('MESH:C566610', 'Disease') :: ['axis'] @entity85 :: ('MESH:D009140', 'Disease') :: ['planar deformation'] @entity95 :: ('9986', 'Species') :: ['rabbit'] @entity902 :: ('MESH:D010984', 'Chemical') :: ['platinum']
@entity95 :: (9986,Species) :: ['rabbit']
