31P NMR spectroscopy senses the microenvironment of the 5′-phosphate group of enzyme-bound pyridoxal 5′-phosphate

In this review it is demonstrated that 31P NMR spectroscopy can be used to elucidate information about the microenvironment around the phosphate group of enzyme-bound pyridoxal 5′-phosphate (PLP). The following information can be obtained for all PLP-dependent enzymes: 1) the protonation state of the 5′-phosphate and its exposure to solvent, and 2) tightness of binding of the 5′-phosphate. In addition, the 5-phosphate can report on the protonation state of the Schiff base lysine in some enzymes. Changes in the 5′-phosphate chemical shift can be used to determine changes in tightness of binding of the phosphate as the reaction pathway is traversed, providing information on the dynamics of the enzyme. 31P NMR spectroscopy is thus an important probe of structure, dynamics and mechanism in native and site-directed mutations of PLP-dependent enzymes. Examples of all of the above are provided in this review. This article is part of a Special Issue entitled: Pyridoxal Phospate Enzymology.

Research highlights
► The pH-dependence of the monoanion to dianion transition of the 5′-phosphate of PLP provides evidence of exposure of the phosphate to solvent.
► 31P NMR can provide a precise description of the microenvironment of the 5′-phosphate of PLP.
► 5′-phosphate binding sites of PLP-dependent enzymes that catalyze β-elimination reactions are all quite similar.