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Iron-dependent formation of homocysteine
Eur J Clin Nutr. 2007 Feb 14; [Epub ahead of print]Iron-dependent
formation of homocysteine from methionine and other thioethers.
Baggott JE, Tamura T.
1Department of Nutrition Sciences, University of Alabama at
Birmingham, Birmingham, AL, USA.
Objective:We tested whether homocysteine is formed from methionine and
other thioethers in vitro and in vivo, because methionine can be
chemically demethylated to homocysteine.Design:In in vitro studies,
chemical conversions of thioethers (methionine, S-adenosylhomocysteine
and cystathionine) into homocysteine were measured under various
aerobic conditions. In humans, oral methionine (0.17 mmol/kg body
weight) loading tests with and without an oral iron dose (ferrous
sulfate, 13 mumol/kg) were performed.Setting:A university setting in
Birmingham, AL, USA.Subjects:A total of five healthy adult subjects
volunteered.Results:The in vitro incubation of methionine, S-
adenosylhomocysteine or cystathionine with chelated iron resulted in
the formation of homocysteine. These conversions were iron- and pH-
dependent (pH optima between 5.0 and 6.0) and it was also chelator-
dependent. In humans, oral methionine loading tests resulted in a 45%
increase in the area-under-the-curve for plasma total homocysteine
concentrations, when iron was given together with
methionine.Conclusion:Our data suggest that iron-dependent chemical
formation of homocysteine can occur in vivo, and contribute to the
plasma total homocysteine pool, since this formation can occur
ceaselessly. We hypothesize that plasma total homocysteine
concentrations reflect, in part, non-protein-bound iron in the
body.European Journal of Clinical Nutrition advance online
publication, 14 February 2007; doi:10.1038/sj.ejcn.1602665.
PMID: 17299471 [PubMed - as supplied by publisher
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formation of homocysteine from methionine and other thioethers.
Baggott JE, Tamura T.
1Department of Nutrition Sciences, University of Alabama at
Birmingham, Birmingham, AL, USA.
Objective:We tested whether homocysteine is formed from methionine and
other thioethers in vitro and in vivo, because methionine can be
chemically demethylated to homocysteine.Design:In in vitro studies,
chemical conversions of thioethers (methionine, S-adenosylhomocysteine
and cystathionine) into homocysteine were measured under various
aerobic conditions. In humans, oral methionine (0.17 mmol/kg body
weight) loading tests with and without an oral iron dose (ferrous
sulfate, 13 mumol/kg) were performed.Setting:A university setting in
Birmingham, AL, USA.Subjects:A total of five healthy adult subjects
volunteered.Results:The in vitro incubation of methionine, S-
adenosylhomocysteine or cystathionine with chelated iron resulted in
the formation of homocysteine. These conversions were iron- and pH-
dependent (pH optima between 5.0 and 6.0) and it was also chelator-
dependent. In humans, oral methionine loading tests resulted in a 45%
increase in the area-under-the-curve for plasma total homocysteine
concentrations, when iron was given together with
methionine.Conclusion:Our data suggest that iron-dependent chemical
formation of homocysteine can occur in vivo, and contribute to the
plasma total homocysteine pool, since this formation can occur
ceaselessly. We hypothesize that plasma total homocysteine
concentrations reflect, in part, non-protein-bound iron in the
body.European Journal of Clinical Nutrition advance online
publication, 14 February 2007; doi:10.1038/sj.ejcn.1602665.
PMID: 17299471 [PubMed - as supplied by publisher
Who loves ya.
Tom
Jesus Was A Vegetarian!
* jesuswasavegetarian.7h . com
Man Is A Herbivore!
* tinyurl . com /a3cc3
DEAD PEOPLE WALKING
* tinyurl . com /zk9fk
