Title
Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate
Document Type
Article
Publication Date
8-23-2001
Abstract
Hen egg-white lysozyme (HEWL) was the first enzyme to have its three-dimensional structure determined by X-ray diffraction techniques. A catalytic mechanism, featuring a long-lived oxocarbenium-ion intermediate, was proposed on the basis of model-building studies. The 'Phillips' mechanism is widely held as the paradigm for the catalytic mechanism of β-glycosidases that cleave glycosidic linkages with net retention of configuration of the anomeric centre. Studies with other retaining β-glycosidases, however, provide strong evidence pointing to a common mechanism for these enzymes that involves a covalent glycosyl-enzyme intermediate, as previously postulated. Here we show, in three different cases using electrospray ionization mass spectrometry, a catalytically competent covalent glycosyl-enzyme intermediate during the catalytic cycle of HEWL. We also show the three-dimensional structure of this intermediate as determined by X-ray diffraction. We formulate a general catalytic mechanism for all retaining β-glycosidases that includes substrate distortion, formation of a covalent intermediate, and the electrophilic migration of C1 along the reaction coordinate.
Publication Source (Journal or Book title)
Nature
First Page
835
Last Page
838
Recommended Citation
Vocadlo, D., Davies, G., Laine, R., & Withers, S. (2001). Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate. Nature, 412 (6849), 835-838. https://doi.org/10.1038/35090602