AI Article Synopsis
- Hydrogen bonding is crucial for the strong binding of the FMN cofactor in flavodoxins and influences their redox properties.
- The study used multidimensional heteronuclear NMR spectroscopy to observe these hydrogen bonding interactions in different redox states of Desulfovibrio vulgaris flavodoxin.
- The findings reveal specific trans-hydrogen-bond couplings and show that both (h)J and regular J coupling constants vary with the redox state, highlighting their relationship with donor-group chemical shifts and donor-acceptor distances.
Article Abstract
Hydrogen bonding plays a key role in the tight binding of the FMN cofactor and the regulation of its redox properties in flavodoxins. Hydrogen bonding interactions can be directly observed in solution by multidimensional heteronuclear NMR spectroscopy through the scalar couplings between donor and acceptor nuclei. Here we report on the detection of intermolecular trans-hydrogen-bond couplings ((h)J) between the flavin ring system and the backbone of Desulfovibrio vulgaris flavodoxin in the oxidized and the two-electron reduced states. For this purpose, experiments are adapted from pulse sequences previously applied to determining (h)J coupling constants in nucleic acid-base pairs and proteins. The resulting (h2)J(N,N), (h4)J(N,N), (h3)J(C,N), and (h1)J(H,N) couplings involve the (15)N(1), (13)C(2), and (15)N(3) nuclei of the pyrimidine moiety of FMN, whereas no such interactions are detectable for (13)C(4) and (15)N(5). Several long-range (15)N-(15)N, (13)C-(15)N, and (1)H-(15)N J-coupling constants within the flavin are obtained as "by-products". The magnitudes of both (h)J and regular J couplings are found to be dependent on the redox state. In general, good correlations between (h)J coupling constants and donor-group (1)H chemical shifts and also crystallographic donor-acceptor distances are observed.
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| http://dx.doi.org/10.1002/cbic.200400171 | DOI Listing |
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