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NMR Relaxometric Investigation on Human Methemoglobin and Fluoromethemoglobin. An Improved Quantitative in Vitro Assay of Human Methemoglobin
Author(s) -
Aime Silvio,
Fasano Mauro,
Paoletti Silvia,
Arnelli Aldo,
Ascenzi Paolo
Publication year - 1995
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910330613
Subject(s) - methemoglobin , relaxation (psychology) , chemistry , proton , hemoglobin , in vitro , nuclear magnetic resonance , analytical chemistry (journal) , chromatography , biochemistry , medicine , physics , quantum mechanics
Longitudinal water proton relaxation rates of methemoglobin solutions show a strong dependence on temperature and pH. The increase of the relaxation rates with temperature is associated with shortened exchange lifetime of the coordinated water molecule. An accurate measurement of the relaxation rate of methemoglobin solutions thus requires careful control of the experimental temperature. This observation prompted the authors to look for an improved version of the relaxometric in vitro determination of methemoglobin. The method is based on transforming methemoglobin into the corresponding fluoromethemoglobin derivative, which shows both a higher relaxivity and a negligible dependence on temperature. The proposed method has been found to be in good agreement with data from spectrophotometric assays.