572-96-3Relevant articles and documents
Assessment of the contribution of NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) to the reduction of vitamin K in wild-type and NQO1-deficient mice
Ingram, Brian O.,Turbyfill, Jared L.,Bledsoe, Peggy J.,Jaiswal, Anil K.,Stafford, Darrel W.
, p. 47 - 54 (2013)
NQO1 [NAD(P)H quinone oxidoreductase 1; also known as DT-diaphorase] is a cytosolic enzyme that catalyses the twoelectron reduction of various quinones including vitamin K. The enzyme may play a role in vitamin K metabolism by reducing vitamin K to vitamin K hydroquinone for utilization in the post-translational γ-glutamyl carboxylation reactions required by several proteins involved in blood coagulation. The aim of the present study was to assess the contribution of NQO1 to vitamin K reduction and haemostasis in an in vivo model. We examined the contribution of NQO1 to haemostasis by examining survival rates in mice poisoned with the anticoagulant warfarin. Supraphysiological amounts of vitamin K sufficiently reversed the effects of warfarin in both wild-type and NQO1-deficient mice. Additionally, vitamin K reductase activities distinct from VKOR (vitamin K epoxide reductase) and NQO1 were measured in vitro from both wild-type and NQO1-defecient mice. The results of the present study suggest that NQO1 does not play a major role in the production of vitamin K hydroquinone and supports the existence of multiple vitamin K reduction pathways. The properties of a NAD(P)H-dependent vitamin K reductase different from NQO1 are described.
Karrer,Simon,Zbinden
, p. 317 (1944)
Detection and quantification of vitamin K1 quinol in leaf tissues
Oostende, Chloe van,Widhalm, Joshua R.,Basset, Gilles J.C.
, p. 2457 - 2462 (2008/12/22)
Phylloquinone (2-methyl-3-phytyl-1,4-naphthoquinone; vitamin K1) is vital to plants. It is responsible for the one-electron transfer at the A1 site of photosystem I, a process that involves turnover between the quinone and semi-quinone forms of phylloquinone. Using HPLC coupled with fluorometric detection to analyze Arabidopsis leaf extracts, we detected a third redox form of phylloquinone corresponding to its fully reduced - quinol-naphthoquinone ring (PhQH2). A method was developed to quantify PhQH2 and its corresponding oxidized quinone (PhQ) counterpart in a single HPLC run. PhQH2 was found in leaves of all dicotyledonous and monocotyledonous species tested, but not in fruits or in tubers. Its level correlated with that of PhQ, and represented 5-10% of total leaf phylloquinone. Analysis of purified pea chloroplasts showed that these organelles accounted for the bulk of PhQH2. The respective pool sizes of PhQH2 and PhQ were remarkably stable throughout the development of Arabidopsis green leaves. On the other hand, in Arabidopsis and tomato senescing leaves, PhQH2 was found to increase at the expense of PhQ, and represented 25-35% of the total pool of phylloquinone. Arabidopsis leaves exposed to light contained lower level of PhQH2 than those kept in the dark. These data indicate that PhQH2 does not originate from the photochemical reduction of PhQ, and point to a hitherto unsuspected function of phylloquinone in plants. The putative origin of PhQH2 and its recycling into PhQ are discussed.
