Crystallization and preliminary crystallographic studies of recombinant dimerization cofactor of transcription factor HNF1/pterin-4 alpha-carbinolamine dehydratase from liver.

The bi-functional protein dimerization cofactor of HNF1 (DCoH)/pterin-4 alpha-carbinolamine dehydratase (PCD) is found in liver cell nuclei bound to the transcription factor hepatocyte nuclear factor 1 (HNF1) as well as in the cytoplasm acting as an enzyme involved in the phenylalanine hydroxylation system. Deficiency of DCoH/PCD activity in liver causes an atypical hyperphenylalaninemia and deficiency in human epidermis is related to the depigmentation disorder vitiligo. DCoH/PCD from rat liver, which is identical to the human protein, was expressed in E. coli, purified to homogeneity and crystallized. The crystals belong to the trigonal space group P3(1)21 (or P3(2)21) with unit cell dimensions of a = b = 106.2 A, c = 197.1 A. Native crystals diffract to a resolution of 2.5 A.