Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH

2015
journal article
article
cris.lastimport.wos2024-04-09T23:04:11Z
dc.abstract.enThe interaction with nitric oxide (NO) is an important aspect of the biological activity of vitamin B12 (Cbl). Whereas the formation of nitroxylcobalamin (CblNO) via the binding of NO to reduced CblCo(II) has been studied in detail before, the possible intracellular formation of CblNO via reduction of nitrocobalamin (CblNO2) is still questionable. To study this further, spectroscopic and kinetic studies on the reaction of CblNO2 with the intracellular antioxidant ascorbic acid (Asc) were performed in aqueous solution at the physiological pH of 7.2. It was found that the redox pathway of this reaction requires anaerobic conditions as a result of the rapid re-oxidation of reduced CblCo(II). In the studied system, both CblOH2 and CblNO2 are reduced to CblCo(II) by ascorbate at pH 7.2, the CblOH2 complex being two orders of magnitude more reactive than CblNO2. Clear evidence for redox cycling between CblOH2/CblNO2 and CblCo(II) under aerobic conditions was observed as an induction period during which all oxygen was used prior to the formation of CblCo(II) in the presence of an excess of ascorbate. No evidence for the intermediate formation of CblNO or NO radicals during the reduction of CblNO2 could be found. Nitrocob(III)alamin can be reduced by ascorbic acid under physiological conditions. The products of the reaction are cob(II)alamin and nitrite ion. This reaction is ca. 200 times slower than the one involving aquacob(III)alamin.pl
dc.affiliationWydział Chemii : Zakład Chemii Nieorganicznejpl
dc.contributor.authorPolaczek, Justyna - 179456 pl
dc.contributor.authorOrzeł, Łukasz - 131198 pl
dc.contributor.authorStochel, Grażyna - 132108 pl
dc.contributor.authorvan Eldik, Rudi - 239234 pl
dc.date.accessioned2015-11-30T07:26:32Z
dc.date.available2015-11-30T07:26:32Z
dc.date.issued2015pl
dc.description.number6pl
dc.description.physical1069-1078pl
dc.description.volume20pl
dc.identifier.doi10.1007/s00775-015-1288-9pl
dc.identifier.eissn1432-1327pl
dc.identifier.issn0949-8257pl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/17260
dc.languageengpl
dc.language.containerengpl
dc.rights.licencebez licencji
dc.subtypeArticlepl
dc.titleMechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pHpl
dc.title.journalJBIC. Journal of Biological Inorganic Chemistrypl
dc.typeJournalArticlepl
dspace.entity.typePublication
cris.lastimport.wos
2024-04-09T23:04:11Z
dc.abstract.enpl
The interaction with nitric oxide (NO) is an important aspect of the biological activity of vitamin B12 (Cbl). Whereas the formation of nitroxylcobalamin (CblNO) via the binding of NO to reduced CblCo(II) has been studied in detail before, the possible intracellular formation of CblNO via reduction of nitrocobalamin (CblNO2) is still questionable. To study this further, spectroscopic and kinetic studies on the reaction of CblNO2 with the intracellular antioxidant ascorbic acid (Asc) were performed in aqueous solution at the physiological pH of 7.2. It was found that the redox pathway of this reaction requires anaerobic conditions as a result of the rapid re-oxidation of reduced CblCo(II). In the studied system, both CblOH2 and CblNO2 are reduced to CblCo(II) by ascorbate at pH 7.2, the CblOH2 complex being two orders of magnitude more reactive than CblNO2. Clear evidence for redox cycling between CblOH2/CblNO2 and CblCo(II) under aerobic conditions was observed as an induction period during which all oxygen was used prior to the formation of CblCo(II) in the presence of an excess of ascorbate. No evidence for the intermediate formation of CblNO or NO radicals during the reduction of CblNO2 could be found. Nitrocob(III)alamin can be reduced by ascorbic acid under physiological conditions. The products of the reaction are cob(II)alamin and nitrite ion. This reaction is ca. 200 times slower than the one involving aquacob(III)alamin.
dc.affiliationpl
Wydział Chemii : Zakład Chemii Nieorganicznej
dc.contributor.authorpl
Polaczek, Justyna - 179456
dc.contributor.authorpl
Orzeł, Łukasz - 131198
dc.contributor.authorpl
Stochel, Grażyna - 132108
dc.contributor.authorpl
van Eldik, Rudi - 239234
dc.date.accessioned
2015-11-30T07:26:32Z
dc.date.available
2015-11-30T07:26:32Z
dc.date.issuedpl
2015
dc.description.numberpl
6
dc.description.physicalpl
1069-1078
dc.description.volumepl
20
dc.identifier.doipl
10.1007/s00775-015-1288-9
dc.identifier.eissnpl
1432-1327
dc.identifier.issnpl
0949-8257
dc.identifier.uri
http://ruj.uj.edu.pl/xmlui/handle/item/17260
dc.languagepl
eng
dc.language.containerpl
eng
dc.rights.licence
bez licencji
dc.subtypepl
Article
dc.titlepl
Mechanistic information on the nitrite-controlled reduction of aquacob(III)alamin by ascorbate at physiological pH
dc.title.journalpl
JBIC. Journal of Biological Inorganic Chemistry
dc.typepl
JournalArticle
dspace.entity.type
Publication

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