title: High pressure31P NMR spectroscopy on guanine nucleotides.
abstract: The31P NMR pressure response of guanine nucleotides bound to proteins has been studied in the past for characterizing the pressure perturbation of conformational equilibria. The pressure response of the31P NMR chemical shifts of the phosphate groups of GMP, GDP, and GTP as well as the commonly used GTP analogs GppNHp, GppCH2p and GTPγS was measured in the absence and presence of Mg2+-ions within a pressure range up to 200 MPa. The pressure dependence of chemical shifts is clearly non-linear. For all nucleotides a negative first order pressure coefficient B1was determined indicating an upfield shift of the resonances with pressure. With exception of the α-phosphate group of Mg2+·GMP and Mg2+·GppNHp the second order pressure coefficients are positive. To describe the data of Mg2+·GppCH2p and GTPγS a Taylor expansion of 3rd order is required. For distinguishing pH effects from pressure effects a complete pH titration set is presented for GMP, as well as GDP and GTP in absence and presence of Mg2+ions using indirect referencing to DSS under identical experimental conditions. By a comparison between high pressure31P NMR data on free Mg2+-GDP and Mg2+-GDP in complex with the proto-oncogene Ras we demonstrate that pressure induced changes in chemical shift are clearly different between both forms.
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Spoerner
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Karl
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Pedro
authors.initials: P
authors.lastname: Lopes
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Hoering
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Karoline
authors.initials: K
authors.lastname: Loeffel
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Nuehs
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Joseph
authors.initials: J
authors.lastname: Adelsberger
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Kremer
authors.affiliation: Centre of Magnetic Resonance in Chemistry and Biomedicine, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany. hans-robert.kalbitzer@ur.de.
authors.forename: Hans Robert
authors.identifier: 0000-0002-6514-2355
authors.initials: HR
authors.lastname: Kalbitzer
mesh_terms: D006150:Guanine Nucleotides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008670:Metals
chemical_list: D006150:Guanine Nucleotides; D008670:Metals
keywords: 31P NMR; GDP; GMP; GTP; GTP analogs; Guanine nucleotide; High pressure NMR spectroscopy