1dr3
From Proteopedia
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2.3 ANGSTROMS CRYSTAL STRUCTURE OF CHICKEN LIVER DIHYDROFOLATE REDUCTASE COMPLEXED WITH THIONADP+ AND BIOPTERIN
Overview
The role of the 3'-carboxamide substituent of NADPH in the reduction of, pteridine substrates as catalyzed by dihydrofolate reductase (EC 1.5.1.3, DHFR) has been investigated by determining crystal structures at 2.3 A of, chicken liver DHFR in a binary complex with oxidized thionicotinamide, adenine dinucleotide (thioNADP+) and in a ternary complex with thioNADP+, and biopterin. These structures are isomorphous with those previously, reported for chicken liver DHFR [Volz, K.W., Matthews, D.A., Alden, R.A., Freer, S. T., Hansch, C., Kaufman, B. T., & Kraut, J. (1982) J. Biol., Chem. 257, 2528-2536]. ThioNADPH, which has a 3'-carbothioamide, substituent in place of a 3'-carboxamide, functions very poorly as a, coenzyme for DHFR [Williams, T. J., Lee, T. K., & Dunlap, R. B. (1977), Arch, Biochem. Biophys. 181, 569-579; Stone, S. R., Mark, A., & Morrison, J. F. (1984) Biochemistry 23, 4340-4346]. Comparisons show that, while, NADP+ and NADPH bind to DHFR with the pyridine ring and 3'-carboxamide, coplanar, the thioamide group is twisted by 23 degrees from the pyridine, plane in both the binary and ternary complexes. This twist appears to be, due to steric conflict between the thioamide sulfur atom and both the, pyridine ring at C4 and the adjacent protein backbone at Ala-9. It results, in an unfavorably close contact between the sulfur and the biopterin, pteridine ring (0.9 A less than the van der Waals separation) which, on, the basis of the refined structure, greatly destabilizes the binding of, biopterin.(ABSTRACT TRUNCATED AT 250 WORDS)
About this Structure
1DR3 is a Single protein structure of sequence from Gallus gallus with CA, TAP and HBI as ligands. Active as Dihydrofolate reductase, with EC number 1.5.1.3 Full crystallographic information is available from OCA.
Reference
Crystal structures of chicken liver dihydrofolate reductase: binary thioNADP+ and ternary thioNADP+.biopterin complexes., McTigue MA, Davies JF 2nd, Kaufman BT, Kraut J, Biochemistry. 1993 Jul 13;32(27):6855-62. PMID:8334118
Page seeded by OCA on Tue Nov 20 13:30:55 2007
