Purification, crystallization, and preliminary crystallographic analysis of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase fromEscherichia coli

Abstract
The phenylalanine-regulated isozyme of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS) from Escherichia coli, its binary complexes with either substrate, phosphoenolpyruvate (PEP), or feedback inhibitor, Phe, and its ternary complexes with either PEP or Phe plus metal cofactor (either Mn2+, Cd2+, or Pb2+) were crystallized from polyethylglycol (PEG) solutions. All crystals of the DAHPS without Phe belong to space group C2, with cell parameters a = 213.5 A, b = 54.3 A, c = 149.0 A, beta = 116.6 degrees. All crystals of the enzyme with Phe also belong to space group C2, but with cell parameters a = 297.1 A, b = 91.4 A, c = 256.5 A, and beta = 148.2 degrees.