Crystal structures of pyruvate phosphate dikinase from maize revealed an alternative conformation in the swiveling-domain motion.

Pyruvate phosphate dikinase (PPDK) reversibly catalyzes the conversion of ATP, phosphate, and pyruvate into AMP, pyrophosphate, and phosphoenolpyruvate (PEP), respectively. Since the nucleotide binding site (in the N-terminal domain) and the pyruvate/PEP binding site (in the C-terminal domain) are separated by approximately 45 A, it has been proposed that an intermediary domain, called the central domain, swivels between these remote domains to transfer the phosphate. However, no direct structural evidence for the swiveling central domain has been found.

Purification, crystallization and preliminary X-ray diffraction studies on pyruvate phosphate dikinase from maize.

Pyruvate phosphate dikinase (PPDK) from maize catalyzes the reversible conversion of ATP, orthophosphate and pyruvate to AMP, pyrophosphate and PEP. In higher plants, this enzyme is believed to be involved in the C(4) dicarboxylic acid pathway. PPDK was crystallized by the vapour-diffusion method using polyethylene glycol as a precipitant.