Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism
Autor(a) principal: | |
---|---|
Data de Publicação: | 2006 |
Outros Autores: | , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Journal of the Brazilian Chemical Society (Online) |
Texto Completo: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000800011 |
Resumo: | Purple acid phosphatases (PAPs) belong to the family of binuclear metallohydrolases and catalyse the hydrolysis of a large group of phosphoester substrates at acidic pH. Despite structural conservation in their active sites PAPs appear to display mechanistic versatility. Here, aspects of the catalytic mechanism of two PAPs are investigated using the inhibitors vanadate and fluoride as probes. While the magnitude of their vanadate inhibition constants are similar the two enzymes differ with respect to the mode of inhibition; vanadate interacts in a non-competitive fashion with pig PAP (Ki = 40 µmol L-1) while it inhibits red kidney bean PAP competitively (Ki = 30 µmol L-1). Similarly, fluoride also acts as a competitive inhibitor for red kidney bean PAP, independent of pH, while the inhibition of pig PAP by fluoride is uncompetitive at low pH and non-competitive at higher pH, independent of metal ion composition. Furthermore, while fluoride acts as a slow-binding inhibitor in pig PAP it binds rapidly to the catalytic site of the red kidney bean enzyme. Since vanadate and fluoride are proposed to act as transition state and nucleophile mimics, respectively, the observed differences in inhibition kinetics indicate subtle but distinct variations in the reaction mechanism of these enzymes. |
id |
SBQ-2_273abcaf2b17c6e9da80f2a1c9f0643c |
---|---|
oai_identifier_str |
oai:scielo:S0103-50532006000800011 |
network_acronym_str |
SBQ-2 |
network_name_str |
Journal of the Brazilian Chemical Society (Online) |
repository_id_str |
|
spelling |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanismpurple acid phosphatasecatalytic mechanismkineticsenzyme inhibitionPurple acid phosphatases (PAPs) belong to the family of binuclear metallohydrolases and catalyse the hydrolysis of a large group of phosphoester substrates at acidic pH. Despite structural conservation in their active sites PAPs appear to display mechanistic versatility. Here, aspects of the catalytic mechanism of two PAPs are investigated using the inhibitors vanadate and fluoride as probes. While the magnitude of their vanadate inhibition constants are similar the two enzymes differ with respect to the mode of inhibition; vanadate interacts in a non-competitive fashion with pig PAP (Ki = 40 µmol L-1) while it inhibits red kidney bean PAP competitively (Ki = 30 µmol L-1). Similarly, fluoride also acts as a competitive inhibitor for red kidney bean PAP, independent of pH, while the inhibition of pig PAP by fluoride is uncompetitive at low pH and non-competitive at higher pH, independent of metal ion composition. Furthermore, while fluoride acts as a slow-binding inhibitor in pig PAP it binds rapidly to the catalytic site of the red kidney bean enzyme. Since vanadate and fluoride are proposed to act as transition state and nucleophile mimics, respectively, the observed differences in inhibition kinetics indicate subtle but distinct variations in the reaction mechanism of these enzymes.Sociedade Brasileira de Química2006-12-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000800011Journal of the Brazilian Chemical Society v.17 n.8 2006reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.1590/S0103-50532006000800011info:eu-repo/semantics/openAccessElliott,Tristan W.Mitic,NataaGahan,Lawrence R.Guddat,Luke W.Schenk,Gerhardeng2007-02-07T00:00:00Zoai:scielo:S0103-50532006000800011Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2007-02-07T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false |
dc.title.none.fl_str_mv |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
title |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
spellingShingle |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism Elliott,Tristan W. purple acid phosphatase catalytic mechanism kinetics enzyme inhibition |
title_short |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
title_full |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
title_fullStr |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
title_full_unstemmed |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
title_sort |
Inhibition studies of purple acid phosphatases: implications for the catalytic mechanism |
author |
Elliott,Tristan W. |
author_facet |
Elliott,Tristan W. Mitic,Nataa Gahan,Lawrence R. Guddat,Luke W. Schenk,Gerhard |
author_role |
author |
author2 |
Mitic,Nataa Gahan,Lawrence R. Guddat,Luke W. Schenk,Gerhard |
author2_role |
author author author author |
dc.contributor.author.fl_str_mv |
Elliott,Tristan W. Mitic,Nataa Gahan,Lawrence R. Guddat,Luke W. Schenk,Gerhard |
dc.subject.por.fl_str_mv |
purple acid phosphatase catalytic mechanism kinetics enzyme inhibition |
topic |
purple acid phosphatase catalytic mechanism kinetics enzyme inhibition |
description |
Purple acid phosphatases (PAPs) belong to the family of binuclear metallohydrolases and catalyse the hydrolysis of a large group of phosphoester substrates at acidic pH. Despite structural conservation in their active sites PAPs appear to display mechanistic versatility. Here, aspects of the catalytic mechanism of two PAPs are investigated using the inhibitors vanadate and fluoride as probes. While the magnitude of their vanadate inhibition constants are similar the two enzymes differ with respect to the mode of inhibition; vanadate interacts in a non-competitive fashion with pig PAP (Ki = 40 µmol L-1) while it inhibits red kidney bean PAP competitively (Ki = 30 µmol L-1). Similarly, fluoride also acts as a competitive inhibitor for red kidney bean PAP, independent of pH, while the inhibition of pig PAP by fluoride is uncompetitive at low pH and non-competitive at higher pH, independent of metal ion composition. Furthermore, while fluoride acts as a slow-binding inhibitor in pig PAP it binds rapidly to the catalytic site of the red kidney bean enzyme. Since vanadate and fluoride are proposed to act as transition state and nucleophile mimics, respectively, the observed differences in inhibition kinetics indicate subtle but distinct variations in the reaction mechanism of these enzymes. |
publishDate |
2006 |
dc.date.none.fl_str_mv |
2006-12-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000800011 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532006000800011 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/S0103-50532006000800011 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
dc.publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
dc.source.none.fl_str_mv |
Journal of the Brazilian Chemical Society v.17 n.8 2006 reponame:Journal of the Brazilian Chemical Society (Online) instname:Sociedade Brasileira de Química (SBQ) instacron:SBQ |
instname_str |
Sociedade Brasileira de Química (SBQ) |
instacron_str |
SBQ |
institution |
SBQ |
reponame_str |
Journal of the Brazilian Chemical Society (Online) |
collection |
Journal of the Brazilian Chemical Society (Online) |
repository.name.fl_str_mv |
Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ) |
repository.mail.fl_str_mv |
||office@jbcs.sbq.org.br |
_version_ |
1750318167722295296 |