Structure of lobster apo-D-glyceraldehyde-3-phosphate dehydrogenase at 3.0 Å resolution

Abstract

Lobster apo-glyceraldehyde-3-phosphate dehydrogenase was prepared by first lowering the pH to 4.8, thus reducing the NAD binding energy, and then separating the enzyme and coenzyme on a Sephadex column. Triclinic crystals were grown from an ammonium sulfate solution at pH 6.2. The apo-structure was initially determined approximately by comparison with the known hologlyceraldehyde-3-phosphate dehydrogenase molecule. The former was then refined using the 222 molecular symmetry with the molecular replacement technique. Only minor conformational differences were observed between apo and holo-glyceraldehyde-3-phosphate dehydrogenase. Trp193 in the "S loop" and the adenine-binding pocket showed the most significant changes.