نتایج جستجو برای: quinone

تعداد نتایج: 5334  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1999
P T Henderson D Jones G Hampikian Y Kan G B Schuster

An anthraquinone-linked duplex DNA oligomer containing 60 base pairs was synthesized by PCR. The strand complementary to the quinone-containing strand has four isolated GG steps, which serve as traps for a migrating radical cation. Irradiation of the quinone leads to electron transfer from the DNA to the quinone forming the anthraquinone radical anion and a base radical cation. The radical cati...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1995
P Dowd Z B Zheng

Vitamin E in the reduced, alpha-tocopherol form shows very modest anticlotting activity. By contrast, vitamin E quinone is a potent anticoagulant. This observation may have significance for field trials in which vitamin E is observed to exhibit beneficial effects on ischemic heart disease and stroke. Vitamin E quinone is a potent inhibitor of the vitamin K-dependent carboxylase that controls bl...

Journal: :Journal of the American Chemical Society 2017
Clinton J Regan David P Walton Oliver S Shafaat Dennis A Dougherty

Mechanistic studies of a general reaction that decages a wide range of substrates on exposure to visible light are described. The reaction involves a photochemically initiated reduction of a quinone mediated by an appended thioether. After reduction, a trimethyl lock system incorporated into the quinone leads to thermal decaging. The reaction could be viewed as an electron-transfer initiated re...

Journal: :Journal of Biological Chemistry 1945

Journal: :Acta Crystallographica Section C Crystal Structure Communications 1998

Journal: :Applied and environmental microbiology 1985
M Shimao I Fujita N Kato C Sakazawa

In a mixed continuous culture of Pseudomonas putida VM15A and Pseudomonas sp. strain VM15C with polyvinyl alcohol (PVA) as the sole source of carbon, growth of the PVA-degrading bacterium VM15C and, hence, PVA degradation were limited by the growth factor, pyrroloquinoline quinone, produced by VM15A. Feeding of a carbon source for VM15A, ethanol, with PVA enhanced pyrroloquinoline quinone produ...

2001
Peter Wan Darryl W. Brousmiche Christy Z. Chen John Cole Matthew Lukeman Musheng Xu

Quinone methides are widely encountered reactive intermediates in the chemistry of phenols and related compounds. This paper summarizes our recent progress in uncovering new and general photochemical methods for forming quinone methides of various structural types in aqueous solution. Their mechanism of formation and subsequent chemistry are also discussed. New examples of excited-state intramo...

Journal: :Biochemical Society transactions 2005
A Y Mulkidjanian M A Kozlova D A Cherepanov

This review is focused on reactions that gate (control) the electron transfer between the primary quinone Q(A) and secondary quinone Q(B) in the photosynthetic reaction centre of Rhodobacter sphaeroides. The results on electron and proton transfer are discussed in relation to structural information and to the steered molecular dynamics simulations of the Q(B) ring flip in its binding pocket. De...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2003
Kimiaki Yamamura Jun Yamane Masao Hashimoto

In the crystal of the title compound, the quinone fragment of the host (1) participates in weak D-A interactions with a neighboring naphthalene moiety of 1 and with the guest molecule via fairly short intermolecular face-to-face contacts. An intermolecular electrostatic interaction between a quinone-oxygen atom and a neighboring quinone ring is suggested by short O...C contacts. There exist sev...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1966
T Watanabe A F Brodie

A role for naphthoquinones in oxidative phosphorylation has been demonstrated with a cell-free system from Mycobacterium phlei.1-3 The natural naphthoquinone of this microorganism, vitamin K9H, functions between the flavoprotein and cytochrome b on the NAD+-linked and malate-vitamin K reductase pathways.3' 4 Evidence has been presented for the existence of a phosphorylative site between the nat...

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