Crystallization and preliminary X-ray diffraction analysis of the active core of human recombinant cystathionine β-synthase:: an enzyme involved in vascular disease

Cystathionine beta -synthase (CBS) is a unique heme enzyme that catalyzes a PLP-dependent condensation of serine and homocysteine to give cystathionine. Deficiency of CBS leads to homocystinuria, an autosomal recessively inherited disease of sulfur metabolism. A truncated form of CBS in which the C-terminal amino-acid residues have been deleted has been prepared. The truncated CBS subunits form a dimer, in contrast to the full-length subunits which form tetramers and higher oligomers. The truncated CBS yielded crystals diffracting to 2.6 Angstrom which belong to space group P3(1) or P3(2). This is the first comprehensive structural investigation of a PLP and heme-containing enzyme.