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Microsomal glutathione transferase 1 exhibits one-third-of-the-sites-reactivity towards glutathione

Johan Ålander, Johan Lengqvist, Peter J Holm, Richard Svensson, Pascal Gerbaux, Robert H.H. van den Heuvel, Hans Hebert, William Griffiths Orcid Logo, Richard N Armstrong, Ralf Morgenstern

Archives of Biochemistry and Biophysics, Volume: 487, Issue: 1, Pages: 42 - 48

Swansea University Author: William Griffiths Orcid Logo

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DOI (Published version): 10.1016/j.abb.2009.04.009

Abstract

The trimeric membrane protein microsomal glutathione transferase 1 (MGST1) possesses glutathione transferase and peroxidase activity. Previous data indicated one active site/trimer whereas structural data suggests three GSH-binding sites. Here we have determined ligand interactions of MGST1 by sever...

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Published in: Archives of Biochemistry and Biophysics
ISSN: 0003-9861
Published: 2009
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URI: https://cronfa.swan.ac.uk/Record/cronfa10949
Abstract: The trimeric membrane protein microsomal glutathione transferase 1 (MGST1) possesses glutathione transferase and peroxidase activity. Previous data indicated one active site/trimer whereas structural data suggests three GSH-binding sites. Here we have determined ligand interactions of MGST1 by several techniques. Nanoelectrospray mass spectrometry of native MGST1 revealed binding of three GSH molecules/trimer and equilibrium dialysis showed three product molecules/trimer (Kd = 320 ± 50 μM). All three product molecules could be competed out with GSH. Reinvestigation of GSH-binding showed one high affinity site per trimer, consistent with earlier data. Using single turnover stopped flow kinetic measurements, Kd could be determined for a low affinity GSH-binding site (2.5 ± 0.5 mM). Thus we can reconcile previous observations and show here that MGST1 contains three active sites with different affinities for GSH and that only the high affinity site is catalytically competent.
College: Faculty of Medicine, Health and Life Sciences
Issue: 1
Start Page: 42
End Page: 48

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