Files in this item
Calcium ions alter monoamine oxidase A activity
Item metadata
dc.contributor.author | Ramsay, Rona R. | |
dc.contributor.author | Armstrong, Stephanie | |
dc.contributor.editor | Miller, Susan | |
dc.contributor.editor | Hille, Russ | |
dc.contributor.editor | Palfrey, Bruce | |
dc.date.accessioned | 2013-08-06T11:01:06Z | |
dc.date.available | 2013-08-06T11:01:06Z | |
dc.date.issued | 2013 | |
dc.identifier.citation | Ramsay , R R & Armstrong , S 2013 , Calcium ions alter monoamine oxidase A activity . in S Miller , R Hille & B Palfrey (eds) , Flavins and Flavoproteins 2011 : Proceedings of the 17th International Symposium IUBMB S13/2011 . Flavins and Flavoproteins , Lulu , 17th Intl Symposium on Flavins and Flavoproteins , Berkeley, CA , United States , 24/07/11 . | en |
dc.identifier.citation | conference | en |
dc.identifier.isbn | 978-1-300-78640-5 | |
dc.identifier.isbn | 130078640X | |
dc.identifier.other | PURE: 21511699 | |
dc.identifier.other | PURE UUID: 357734fd-3234-4d04-8e8e-d9460561189a | |
dc.identifier.other | ORCID: /0000-0003-1535-4904/work/34907354 | |
dc.identifier.uri | https://hdl.handle.net/10023/3928 | |
dc.description | S. Armstrong graduated from the University of St Andrews in 2011 | en |
dc.description.abstract | Activation of the flavoprotein monoamine oxidase A (MAO A) by calcium ions has been reported in isolated mitochondria, in cell lines, and in vivo. Enhanced MAO A activity has been associated with a rise in oxidative damage (1,2), and with apoptosis in a neuronal cell line (5). Here, purified human MAO A and membrane-bound MAO A and B were used to investigate the direct regulation of MAO activity by Ca2+ ions. At fixed substrate concentration the activity of purified MAO A was stimulated (<20%) by Ca2+ over a physiological range, a much smaller effect than observed in cells; Mg2+ and Mn2+ had no effect. However, when chelating agents (EDTA or EGTA) were added to remove divalent ions present in the water, MAO A activity was increased, but addition of 1 mM Ca2+ to the chelating buffer resulted in inhibition of activity requiring 10 min to reach the minimum. When assayed in HEPES buffer (50 mM, pH 7.4) without chelator, Ca2+ caused mixed-type inhibition of kynuramine oxidation with a Ki of 0.3 mM for binding to free enzyme. We conclude that Ca2+ (but not Mg2+ or Mn2+) interacts directly with purified MAO A to change the kinetic parameters resulting in decreased activity. In contrast, with membrane-bound MAO A (but not membrane-bound MAO B), Ca2+ enhances activity by doubling the Vmax without a change in KM. Recently, molecular dynamics simulations suggested that membrane attachment altered the conformational dynamics of MAO A and facilitated the opening of the substrate tunnel. The data here are consistent with a conformational change induced by Ca2+, the effect of which is different when the enzyme is stabilised in the membrane. | |
dc.format.extent | 5 | |
dc.language.iso | eng | |
dc.publisher | Lulu | |
dc.relation.ispartof | Flavins and Flavoproteins 2011 | en |
dc.relation.ispartofseries | Flavins and Flavoproteins | en |
dc.rights | (c) The authors | en |
dc.subject | QP Physiology | en |
dc.subject.lcc | QP | en |
dc.title | Calcium ions alter monoamine oxidase A activity | en |
dc.type | Conference item | en |
dc.description.version | Preprint | en |
dc.contributor.institution | University of St Andrews. School of Biology | en |
dc.contributor.institution | University of St Andrews. Biomedical Sciences Research Complex | en |
This item appears in the following Collection(s)
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.