Enhanced activity of the plasma membrane oxidoreductase in circulating lymphocytes from insulin-dependent diabetes mellitus patients |
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Authors: | Lenaz Giorgio Paolucci Ugo Fato Romana D'Aurelio Marilena Parenti Castelli Giovanna Sgarbi Gianluca Biagini Graziella Ragni Luca Salardi Silvana Cacciari Emanuele |
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Affiliation: | Dipartimento di Biochimica, Università di Bologna, Via Irnerio 48, Bologna 40126, Italy. lenaz@biocfarm.unibo.it |
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Abstract: | Circulating human lymphocytes contain a transmembrane oxidoreductase (PMOR) capable of reducing dichlorophenol indophenol (DCIP) by endogenous reductants, presumably NADH. Membranes from lymphocytes obtained from buffy coats contain a NADH DCIP reductase having a K(m) of about 1 microM and almost insensible to dicoumarol. The PMOR of lymphocytes from insulin-dependent diabetic patients is higher than that from age-matched controls and, in addition, has a dicoumarol-sensitive component, lacking in most controls, presumably due to membrane association of DT-diaphorase. The increase of PMOR in diabetes is likely due to overexpression of the enzyme, in view of the very low K(m) for NADH indicating that, in intact cells, the enzyme is practically saturated with the reductant substrate. |
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Keywords: | insulin-dependent diabetes mellitus plasma membrane oxidoreductase DT-diaphorase lymphocytes |
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