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Molecular Recognition and Screening Using a ¹⁵N Group Selective STD NMR Method

Katalin E. Kövér,*^† Patrick Groves,^‡ Jesús Jiménez-Barbero,^§ and Gyula Batta

Contribution from the Department of Inorganic and Analytical Chemistry and Department of Biochemistry, Centre of Arts, Humanities and Sciences, University of Debrecen, Egyetem tr 1, H-4010 Debrecen, Hungary, School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, and Department of Protein Science, Centro de Investigaciones Biolgicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain

J. Am. Chem. Soc., 2007, 129 (37), pp 11579–11582

DOI: 10.1021/ja073291l

Publication Date (Web): August 28, 2007

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

†

Department of Inorganic and Analytical Chemistry, University of Debrecen.

‡

University of Ulster.

Centro de Investigaciones Biológicas.

Department of Biochemistry, Centre of Arts, Humanities and Sciences, University of Debrecen.

, kover@tigris.unideb.hu

Abstract

We present a novel saturation transfer difference (STD) experiment where group selective (GS) saturation of amide protons in ¹⁵N labeled hosts is achieved. It is demonstrated that a train of BIRD^d pulses that inverts only protons attached to ¹⁵N indeed results in saturation of the amide protons, while the background proton magnetization is much less affected. The undesired effect of partial saturation of the unlabeled protons can be completely cancelled out in difference spectra by switching the ¹⁵N carrier between the on- and the off-resonance frequencies. As a result, clean and artifact-free STD spectra are obtained without the need of time-consuming optimization of experimental parameters and acquiring control spectra in the absence of the host. The use of the ¹⁵N-GS STD experiment is demonstrated for the case of a glycopeptide antibiotic (dimeric eremomycin)−cell-wall analogue peptide (N−Ac−d-Ala) model system where the host and guest ¹H signals overlap. The application seems feasible for ligand screening against proteins without the prerequisite of a clean on-resonance frequency or defined ligand library. The new experiment can be used as the basis for studying intermolecular interactions where the standard STD experiment is difficult to optimize.

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