1H and 15N NMR resonance assignments and solution secondary structure of oxidized Desulfovibrio desulfuricans flavodoxin.

Sequence-specific 1H and 15N resonance assignments have been made for 137 of the 146 nonprolyl residues in oxidized Desulfovibrio desulfuricans [Essex 6] flavodoxin. Assignments were obtained by a concerted analysis of the heteronuclear three-dimensional 1H-15N NOESY-HMQC and TOCSY-HMQC data sets, recorded on uniformly 15N-enriched protein at 300 K. Numerous side-chain resonances have been partially or fully assigned. Residues with overlapping 1HN chemical shifts were resolved by a three-dimensional 1H-15N HMQC-NOESY-HMQC spectrum. Medium- and long-range NOEs, 3JNH alpha coupling constants, and 1HN exchange data indicate a secondary structure consisting of five parallel beta-strands and four alpha-helices with a topology similar to that of Desulfovibrio vulgaris [Hildenborough] flavodoxin. Prolines at positions 106 and 134, which are not conserved in D. vulgaris flavodoxin, contort the two C-terminal alpha-helices.