Acid dissociation constants of uridine-5 %26apos;-diphosphate compounds determined by (31)phosphorus nuclear magnetic resonance spectroscopy and internal pH referencing

作者：Jancan Igor; Macnaughtan Megan A^*

来源：Analytica Chimica Acta, 2012, 749: 63-69.

DOI：10.1016/j.aca.2012.08.052

• (31)Phosphorus
• Nuclear magnetic resonance
• Uridine
• 5 %26apos
• -diphosphate-N-acetylglucosamine
• Acid dissociation
• pH reference
• Thio-analog

The acid dissociation constant (pK(a)) of small, biological molecules is an important physical property used for investigating enzyme mechanisms and inhibitor design. For phosphorus-containing molecules, the P-31 nuclear magnetic resonance (NMR) chemical shift is sensitive to the local chemical environment, particularly to changes in the electronic state of the molecule. Taking advantage of this property, we present a P-31 NMR approach that uses inorganic phosphate buffer as an internal pH reference to determine the pK(a) values of the imide and second diphosphate of uridine-5%26apos;-diphosphate compounds, including the first reported values for UDP-GlcNAc and UDP-S-GlcNAc. New methods for using inorganic phosphate buffer as an internal pH reference, involving mathematical correction factors and careful control of the chemical shift reference sample, are illustrated. A comparison of the newly determined imide and diphosphate pK(a) values of UDP, UDP-GlcNAc, and UDP-S-GIcNAc with other nucleotide phosphate and thio-analogs reveals the significance of the monosaccharide and sulfur position on the pK(a) values.

• 出版日期2012-10-24