caa a22 4500 477136362 CHVBK 20180405111719.0 cr unu---uuuuu 170330e19970401xx s 000 0 eng 10.1023/A:1018670623695 doi (NATIONALLICENCE)springer-10.1023/A:1018670623695 Floating stereospecific assignment revisited: Application to an 18 kDa protein and comparison with J-coupling data [Elektronische Daten] [Rutger Folmer, Cornelis Hilbers, Ruud Konings, Michael Nilges] We report a floating chirality procedure to treat nonstereospecifically assigned methylene orisopropyl groups in the calculation of protein structures from NMR data using restrainedmolecular dynamics and simulated annealing. The protocol makes use of two strategies toinduce the proper conformation of the prochiral centres: explicit atom ‘swapping' followingan evaluation of the NOE energy term, and atom ‘floating' by reducing the angle andimproper force constants that enforce a defined chirality at the prochiral centre. The individualcontributions of both approaches have been investigated. In addition, the effects of accuracyand precision of the interproton distance restraints were studied. The model system employedis the 18 kDa single-stranded DNA binding protein encoded by Pseudomonas bacteriophagePf3. Floating chirality was applied to all methylene and isopropyl groups that give rise to non-degenerate NMR signals, and the results for 34 of these groups were compared to J-couplingdata. We conclude that floating stereospecific assignment is a reliable tool in protein structurecalculation. Its use is beneficial because it allows the distance restraints to be extracteddirectly from the measured peak volumes without the need for averaging or addingpseudoatom corrections. As a result, the calculated structures are of a quality almostcomparable to that obtained with stereospecific assignments. As floating chirality furthermoreis the only approach treating prochiral centres that ensures a consistent assignment of the twoproton frequencies in a single structure, it seems to be preferable over using pseudoatoms or(R-6) averaging. Kluwer Academic Publishers, 1997 Structure calculation nationallicence Floating chirality nationallicence Stereospecific assignment nationallicence Simulated annealing nationallicence ssDNA binding protein nationallicence Folmer Rutger Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut Hilbers Cornelis Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut Konings Ruud Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut Nilges Michael European Molecular Biology Laboratory, Meyerhofstrasse 1, D-6900, Heidelberg, Germany aut Journal of Biomolecular NMR Kluwer Academic Publishers 9/3(1997-04-01), 245-258 0925-2738 9:3<245 1997 9 10858 https://doi.org/10.1023/A:1018670623695 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1018670623695 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Folmer Rutger Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut NATIONALLICENCE 700 1- Hilbers Cornelis Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut NATIONALLICENCE 700 1- Konings Ruud Nijmegen SON Research Center, Laboratory of Biophysical Chemistry, University of Nijmegen, Toernooiveld, 6525 ED, Nijmegen, The Netherlands aut NATIONALLICENCE 700 1- Nilges Michael European Molecular Biology Laboratory, Meyerhofstrasse 1, D-6900, Heidelberg, Germany aut NATIONALLICENCE 773 0- Journal of Biomolecular NMR Kluwer Academic Publishers 9/3(1997-04-01), 245-258 0925-2738 9:3<245 1997 9 10858 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer