CRYSTALLIZATION AND PRELIMINARY STRUCTURE DETERMINATION OF PORCINE ALDEHYDE REDUCTASE FROM 2 CRYSTAL FORMS

Aldehyde reductase from porcine kidney has been crystallized from buff ered ammonium sulfate solutions. Two crystal forms are monoclinic spac e group P2(1), with a = 56.2, b = 98.1, c = 73.2 angstrom, beta = 112. 5-degrees and a = 92.4, b = 62. 1, c = 59.0 angstrom, beta = 94.60. A third crystal form is hexagonal with a = b = 166.0, c = 66.0 angstrom, alpha = beta = 90.0-degrees and gamma = 120.0-degrees. Molecular-repl acement structure solutions have been successfully obtained for the tw o monoclinic crystal forms. The crystallographic R factor at 8-2.8 ang strom resolution for the two monoclinic crystal forms is currently 0.2 3 and 0.25, respectively. There are two molecules per asymmetric unit related by a non-crystallographic twofold axis. The aldehyde reductase models are supported by the arrangement of the molecules in their res pective unit cells and by electron densities corresponding to amino-ac id side chains not included in the search structures.