Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands.
The kinetics of azide and fluroide binding to various monomeric and tetrameric ferric hemoproteins (sperm whale Mb, isolated alpha and beta chains of human Hb reacted with p-chloromercuribenzoate, dromeday, ox and human Hb) has been investigated (at pH 6.5 and 20 degrees C over a large range (20 mic...
Published in: | European Journal of Biochemistry |
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1996
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Online Access: | http://hdl.handle.net/11581/201102 https://doi.org/10.1111/j.1432-1033.1996.00049.x http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1996.00049.x/full |
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ftuncamerinoiris:oai:pubblicazioni.unicam.it:11581/201102 2024-04-14T08:20:07+00:00 Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. Coletta, Massimo Cerroni, Loredana Giardina, Bruno Amiconi, Gino ANGELETTI, Mauro DE SANCTIS, Giampiero ASCENZI, Paolo Coletta, Massimo Angeletti, Mauro DE SANCTIS, Giampiero Cerroni, Loredana Giardina, Bruno Amiconi, Gino Ascenzi, Paolo 1996 STAMPA http://hdl.handle.net/11581/201102 https://doi.org/10.1111/j.1432-1033.1996.00049.x http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1996.00049.x/full eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:A1996TQ25600005 volume:235 issue:1 firstpage:49 lastpage:53 numberofpages:4 journal:EUROPEAN JOURNAL OF BIOCHEMISTRY http://hdl.handle.net/11581/201102 doi:10.1111/j.1432-1033.1996.00049.x info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-0030042056 http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1996.00049.x/full info:eu-repo/semantics/article 1996 ftuncamerinoiris https://doi.org/10.1111/j.1432-1033.1996.00049.x 2024-03-21T20:36:40Z The kinetics of azide and fluroide binding to various monomeric and tetrameric ferric hemoproteins (sperm whale Mb, isolated alpha and beta chains of human Hb reacted with p-chloromercuribenzoate, dromeday, ox and human Hb) has been investigated (at pH 6.5 and 20 degrees C over a large range (20 microM to 2 M) of ligand concentration. It has been observed that the pseuo-first-order rate constant for azide binding to the hemoproteins investigated does not increase linearly with ligand concentration, but tends to level off toward an asymptomatic concentration-independent value typical for each hemoprotein. This behavior, which has been detected only by an investigation covering an unusually large range of ligand concentrations appears to be independent of the ionic strength, and it underlies the existence of a rate-limiting step in the dynamic pathway of azide binding to ferric hemoproteins, which is detectable whenever the observed pseudo- first-order rate constant becomes faster than a given value characteristic of the specific hemoprotein. Such a behavior is not observed in the case of fluroide binding probably because the pesudo- first-order rate constant for this ligand is much slower and never attains a value faster than that of the rate-limiting step. In general terms, this feature should involve a conformational equilibrium between at least two forms (possibly related to the interaction of H2O with distal histidine and its exchange with the bulk solvent) which modulates the access of the anionic ligand into the heme pocket and its reaction with the ferric iron. Article in Journal/Newspaper Sperm whale CAMPUS Pubblicazioni Scientifiche Unicam (Università di Camerino) European Journal of Biochemistry 235 1-2 49 53 |
institution |
Open Polar |
collection |
CAMPUS Pubblicazioni Scientifiche Unicam (Università di Camerino) |
op_collection_id |
ftuncamerinoiris |
language |
English |
description |
The kinetics of azide and fluroide binding to various monomeric and tetrameric ferric hemoproteins (sperm whale Mb, isolated alpha and beta chains of human Hb reacted with p-chloromercuribenzoate, dromeday, ox and human Hb) has been investigated (at pH 6.5 and 20 degrees C over a large range (20 microM to 2 M) of ligand concentration. It has been observed that the pseuo-first-order rate constant for azide binding to the hemoproteins investigated does not increase linearly with ligand concentration, but tends to level off toward an asymptomatic concentration-independent value typical for each hemoprotein. This behavior, which has been detected only by an investigation covering an unusually large range of ligand concentrations appears to be independent of the ionic strength, and it underlies the existence of a rate-limiting step in the dynamic pathway of azide binding to ferric hemoproteins, which is detectable whenever the observed pseudo- first-order rate constant becomes faster than a given value characteristic of the specific hemoprotein. Such a behavior is not observed in the case of fluroide binding probably because the pesudo- first-order rate constant for this ligand is much slower and never attains a value faster than that of the rate-limiting step. In general terms, this feature should involve a conformational equilibrium between at least two forms (possibly related to the interaction of H2O with distal histidine and its exchange with the bulk solvent) which modulates the access of the anionic ligand into the heme pocket and its reaction with the ferric iron. |
author2 |
Coletta, Massimo Angeletti, Mauro DE SANCTIS, Giampiero Cerroni, Loredana Giardina, Bruno Amiconi, Gino Ascenzi, Paolo |
format |
Article in Journal/Newspaper |
author |
Coletta, Massimo Cerroni, Loredana Giardina, Bruno Amiconi, Gino ANGELETTI, Mauro DE SANCTIS, Giampiero ASCENZI, Paolo |
spellingShingle |
Coletta, Massimo Cerroni, Loredana Giardina, Bruno Amiconi, Gino ANGELETTI, Mauro DE SANCTIS, Giampiero ASCENZI, Paolo Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
author_facet |
Coletta, Massimo Cerroni, Loredana Giardina, Bruno Amiconi, Gino ANGELETTI, Mauro DE SANCTIS, Giampiero ASCENZI, Paolo |
author_sort |
Coletta, Massimo |
title |
Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
title_short |
Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
title_full |
Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
title_fullStr |
Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
title_full_unstemmed |
Kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
title_sort |
kinetic evidence for the existence of a rate-limiting step in the reaction of ferric hemoproteins with anionic ligands. |
publishDate |
1996 |
url |
http://hdl.handle.net/11581/201102 https://doi.org/10.1111/j.1432-1033.1996.00049.x http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1996.00049.x/full |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:A1996TQ25600005 volume:235 issue:1 firstpage:49 lastpage:53 numberofpages:4 journal:EUROPEAN JOURNAL OF BIOCHEMISTRY http://hdl.handle.net/11581/201102 doi:10.1111/j.1432-1033.1996.00049.x info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-0030042056 http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1996.00049.x/full |
op_doi |
https://doi.org/10.1111/j.1432-1033.1996.00049.x |
container_title |
European Journal of Biochemistry |
container_volume |
235 |
container_issue |
1-2 |
container_start_page |
49 |
op_container_end_page |
53 |
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1796298335092473856 |