High pressure (31)P NMR spectroscopy on guanine nucleotides.
 

High pressure (31)P NMR spectroscopy on guanine nucleotides.

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J Biomol NMR. 2016 Dec 23;:

Authors: Spoerner M, Karl M, Lopes P, Hoering M, Loeffel K, Nuehs A, Adelsberger J, Kremer W, Kalbitzer HR

Abstract
The (31)P 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 the (31)P NMR chemical shifts of the phosphate groups of GMP, GDP, and GTP as well as the commonly used GTP analogs GppNHp, GppCH2p and GTP?S was measured in the absence and presence of Mg(2+)-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 B 1 was determined indicating an upfield shift of the resonances with pressure. With exception of the ?-phosphate group of Mg(2+)·GMP and Mg(2+)·GppNHp the second order pressure coefficients are positive. To describe the data of Mg(2+)·GppCH2p and GTP?S 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 Mg(2+) ions using indirect referencing to DSS under identical experimental conditions. By a comparison between high pressure (31)P NMR data on free Mg(2+)-GDP and Mg(2+)-GDP in complex with the proto-oncogene Ras we demonstrate that pressure induced changes in chemical shift are clearly different between both forms.


PMID: 28012125 [PubMed - as supplied by publisher]



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