Emerging from pseudo-symmetry: The redetermination of human carbonic anhydrase II in monoclinic P21 with a doubled a axis

Abstract

The crystal structure of human carbonic anhydrase II in the monoclinic P21 space group with a doubled a axis from that of the usually observed unit cell has recently been reported, with one of the two molecules in the asymmetric unit demonstrating rotational disorder [Robbins et al. (2010), Acta Cryst. D66, 628-634]. The structure has been redetermined, with the coordinates of both pseudo-symmetrically related molecules in the crystallographic asymmetric unit translated by x′ = x 1/4, and no rotational disorder is observed. This corresponds to a different choice of how the four molecules in the unit cell should be grouped into pairs that represent a single asymmetric unit. © 2010 International Unin of Crystallography Printed in Singapore-all rights reserved.