Structural insights into the loss of catalytic competence in pectate lyase activity at low pH.

Autor: Ali S; Institut Laue Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France; School of Biological and Chemical Sciences, Queen Mary University of London, Department of Chemistry & Biochemistry, Mile End Road, London E1 4NS, United Kingdom., Søndergaard CR; Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark., Teixeira S; Institut Laue Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France; EPSAM, Keele University, Staffordshire ST5 5BG, United Kingdom., Pickersgill RW; School of Biological and Chemical Sciences, Queen Mary University of London, Department of Chemistry & Biochemistry, Mile End Road, London E1 4NS, United Kingdom. Electronic address: r.w.pickersgill@qmul.ac.uk.
Jazyk: angličtina
Zdroj: FEBS letters [FEBS Lett] 2015 Oct 24; Vol. 589 (21), pp. 3242-6. Date of Electronic Publication: 2015 Sep 28.
DOI: 10.1016/j.febslet.2015.09.014
Abstrakt: Pectate lyase, a family 1 polysaccharide lyase, catalyses cleavage of the α-1,4 linkage of the polysaccharide homogalacturonan via an anti β-elimination reaction. In the Michaelis complex two calcium ions bind between the C6 carboxylate of the d-galacturonate residue and enzyme aspartates at the active centre (+1 subsite), they withdraw electrons acidifying the C5 proton facilitating its abstraction by the catalytic arginine. Here we show that activity is lost at low pH because protonation of aspartates results in the loss of the two catalytic calcium-ions causing a profound failure to correctly organise the Michaelis complex.
(Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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