title: The Z isomer of 2,4-diaminofuro[2,3-d]pyrimidine antifolate promotes unusual crystal packing in a human dihydrofolate reductase ternary complex.
abstract: The crystal structure of the ternary complex of human dihydrofolate reductase (hDHFR) with NADPH and the Z isomer of 2,4-diamino-5-[2-(2'-methoxyphenyl)propenyl]-furo[2,3-d]pyrimidine (Z1) shows that the Z isomer binds in the normal antifolate orientation in which the furo oxygen occupies the 8-amino position observed in the binding of 2,4-diaminopteridine antifolates such as methotrexate and with the methoxyphenyl moiety cis to and coplanar with the furo[2,3-d]pyrimidine ring. The hDHFR ternary complex crystallized in the orthorhombic space group P2(1)2(1)2(1) and its structure was refined to 1.7 A resolution. Although other hDHFR complexes crystallize in this space group, these data provide only the second example of an unusual packing arrangement in which the conserved active-site Arg70 forms a salt bridge to the side chain of Glu44 from a symmetry-related molecule. As a result, the conformations of Phe31 and Gln35 shift with respect to those observed in the structure of mouse DHFR bound to Z1, which crystallizes in the monoclinic space group P2(1) and shows that Gln35 interacts with Arg70.
authors: Structural Biology Department, Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA. cody@hwi.buffalo.edu
authors: Vivian
authors: V
authors: Cody
authors: Jim
authors: J
authors: Pace
authors: Lu
authors: L
authors: Lin
authors: Aleem
authors: A
authors: Gangjee
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D005493:Folic Acid Antagonists / Q000737:chemistry*; D006801:Humans; D007536:Isomerism; D008958:Models, Molecular; D011487:Protein Conformation; D011743:Pyrimidines / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry*
chemical_list: D005493:Folic Acid Antagonists; D011743:Pyrimidines; D011994:Recombinant Proteins; D013762:Tetrahydrofolate Dehydrogenase