1h6m
From Proteopedia
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| , resolution 1.64Å | |||||||
|---|---|---|---|---|---|---|---|
| Sites: | , and | ||||||
| Ligands: | , , | ||||||
| Activity: | Lysozyme, with EC number 3.2.1.17 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
COVALENT GLYCOSYL-ENZYME INTERMEDIATE OF HEN EGG WHITE LYSOZYME
Overview
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 beta-glycosidases that cleave glycosidic linkages with net retention of configuration of the anomeric centre. Studies with other retaining beta-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 beta-glycosidases that includes substrate distortion, formation of a covalent intermediate, and the electrophilic migration of C1 along the reaction coordinate.
About this Structure
1H6M is a Single protein structure of sequence from Gallus gallus. Full crystallographic information is available from OCA.
Reference
Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate., Vocadlo DJ, Davies GJ, Laine R, Withers SG, Nature. 2001 Aug 23;412(6849):835-8. PMID:11518970
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