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RESEARCH PRODUCT

Interaction of Oxygen Partial Pressure and Energy Metabolism with the Relaxation Rate of Inorganic Phosphate: A 31P NMR Study

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It is well known that oxygen molecules present in liquid or solid samples can shorten NMR spin-lattice relaxation times (T1) of the nucleus under investigation. Several studies have shown large decrements of 1H, 13C, and 19F relaxation times mediated by the O2 molecule (Lees and Muller, 1961; Ohuchi et al., 1979; Fishman et al., 1989). The positions of the 3lp atoms in phosphate compounds are stereometrically similar to some 13C atoms in organic compounds, and thus an effect of oxygen on the 31P T1 is expected. Recently, we have shown (Okunieff et al., 1988) that oxygen breathing can significantly reduce the T1 of 31p in the inorganic phosphate molecule (Pi). The degree to which this change was mediated by the O2 molecule compared to secondary enzymatic processes that are also augmented when 100% oxygen is inspired (Okunieff et al., 1989), however is unknown.