Phosphoenolpyruvate and Mg2+ Binding to Pyruvate Kinase Monitored by Infrared Spectroscopy

What is it about?

Phosphenolpyruvate (PEP) binding to pyruvate kinase was studied for the first time with reaction-induced infrared difference spectroscopy and isotope-editing of the spectrum of the bound ligand. The method enables a very sensitive detection of the absorbance changes induced by binding. The conformational change of the protein and the structure of the bound ligand were analysed. While the structure of the bound ligand was distorted upon binding to the protein, this distortion was only to a small extent directed toward a dissociative transition state of the phosphate transfer reaction.

Featured Image

Why is it important?

Enzymes may distort the structure of substrates when they bind. Experimental evidence for this is important to understand the catalytic mechanism. In this case, substrate distortion was detected but it was not directed towards the structure in a dissociative transition state for phosphate transfer. The work demonstrates also the excellent sensitivity and reproducibility of data obtained with a little applied method to initiate protein reactions in infrared spectroscopy. See also our publication on this method: M. Krasteva, S. Kumar, A. Barth (2006), Spectroscopy 20, 89-94, A dialysis accessory for attenuated total reflection infrared spectroscopy.