Enhanced activity of the plasma membrane oxidoreductase in circulating lymphocytes from insulin-dependent diabetes mellitus patients.
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.
Lenaz
Giorgio
G
Dipartimento di Biochimica, Università di Bologna, Via Irnerio 48, Bologna 40126, Italy. lenaz@biocfarm.unibo.it
Paolucci
Ugo
U
Fato
Romana
R
D'Aurelio
Marilena
M
Parenti Castelli
Giovanna
G
Sgarbi
Gianluca
G
Biagini
Graziella
G
Ragni
Luca
L
Salardi
Silvana
S
Cacciari
Emanuele
E
D000293:Adolescent; D000328:Adult; D002462:Cell Membrane / Q000201:enzymology; D002648:Child; D003600:Cytosol / Q000201:enzymology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000201:enzymology* / Q000473:pathology; D001728:Dicumarol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D009243:NAD / Q000097:blood; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000096:biosynthesis / Q000097:blood; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis / Q000097:blood / Q000378:metabolism*
D004791:Enzyme Inhibitors; D009243:NAD; D001728:Dicumarol; D009247:NADH, NADPH Oxidoreductases; D016660:NAD(P)H Dehydrogenase (Quinone)