Further studies on the catalytic mechanism of human liver alpha-L-fucosidase.
Publication/Presentation Date
3-18-1987
Abstract
Radiolabeling of human liver alpha-L-fucosidase (alpha-L-fucoside fucohydrolase, EC 3.2.1.51) with [1-3H]conduritol C trans-epoxide revealed that there are four active sites per tetrameric enzyme complex. Solvent isotope effect experiments give evidence for a proton transfer at the rate-limiting step in catalysis. Transglycosylase activity was observed using methanol as an alternative glycone acceptor to produce methyl alpha-L-fucoside, suggesting that alpha-L-fucose is formed when water is the acceptor. Initial burst kinetics experiments suggest that a glycosyl-enzyme intermediate is formed, although the magnitude of the burst is not stoichiometric with the number of active sites. These data, along with previous results, suggest a general acid-general base catalytic mechanism involving double inversion of stereochemistry at C-1 of fucose, as well as the formation of either a covalent glycosyl-enzyme intermediate or a tight ion pair between a charged active-site residue and a hypothetical fucosyl oxocarbonium ion intermediate.
Volume
912
Issue
1
First Page
132
Last Page
138
ISSN
0006-3002
Published In/Presented At
White, W. J., Jr, Schray, K. J., Legler, G., & Alhadeff, J. A. (1987). Further studies on the catalytic mechanism of human liver alpha-L-fucosidase. Biochimica et biophysica acta, 912(1), 132–138. https://doi.org/10.1016/0167-4838(87)90256-1
Disciplines
Medicine and Health Sciences
PubMedID
3828350
Department(s)
Department of Medicine
Document Type
Article