Chemical and bacterial reduction of azo-probes: monitoring a conformational change using fluorescence spectroscopy

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• 作者：Nicholas J.W. Rattray^a ; ^{nicholas.rattray@manchester.ac.uk} ; Waleed A. Zalloum^a ; David Mansell^a ; Joe Latimer^a ; Mohammed Jaffar^b ; Elena V. Bichenkova^a ; ^{elena.bichenkova@manchester.ac.uk} ; Sally Freeman^a ; ^{sally.freeman@manchester.ac.uk}
• 关键词：Fluorescent probe ; Dimer ; Conformational lock ; Azo-reductase ; Escherichia coli ; AMBER
• 刊名：Tetrahedron
• 出版年：2013
• 出版时间：1 April, 2013
• 年：2013
• 卷：69
• 期：13
• 页码：2758-2766
• 全文大小：836 K

文摘

Sterically constrained probes 2,4-O-bisdansyl-6,7-diazabicyclo[3.2.1]oct-6-ene (8) and 2,4-O-bispyrenoyl-6,7-diazabicyclo[3.2.1]oct-6-ene (9) exhibit specific dimer fluorescent characteristics (¦Ë_max 555?nm and 511?nm, respectively), attributed to the 2,4-diaxial arrangement of the dansyl or pyrene groups. Reduction of the azo-conformational locking group in (8) and (9) yielded 1,3-bisdansyl-4,6-diaminocyclohexane (16) and 1,3-bispyrenoyl-4,6-diaminocyclohexane (17) in the tetra-equatorial chair conformation, thus minimising interaction of the bisdansyl or bispyrenoyl groups. This induces a change in fluorescence from a cooperative green emission dimer band to a blue-shifted, monomer type fluorescence, with ¦Ë_max 448?nm and 396?nm for the reduced forms (16) and (17), respectively. The azo-bond conformational lock can either be reduced under biomimetic conditions (using sodium dithionite) or with bacteria (Clostridium perfringens or Escherichia coli) utilising azo-reductase enzymes. These fluorescent probes have the potential to specifically detect azo-reductase expressing bacteria.