Reaction of Oxidized CuZnSOD with Polyphenols  

作　　者：Jack S. Summers Benjamin Hickman Megan E. Arrington Bradley S. Stadelman Julia L. Brumaghim Michelle R. Yost Jeffrey D. Schmitt Mariah Hornby Stacy Sprague Jack S. Summers;Benjamin Hickman;Megan E. Arrington;Bradley S. Stadelman;Julia L. Brumaghim;Michelle R. Yost;Jeffrey D. Schmitt;Mariah Hornby;Stacy Sprague(Department of Chemistry and Physics, Western Carolina University, Cullowhee, NC, USA;Department of Chemistry, Clemson University, Clemson, SC, USA;The Bent Creek Institute, The North Carolina Arboretum, Asheville, NC, USA)

机构地区：[1]Department of Chemistry and Physics, Western Carolina University, Cullowhee, NC, USA [2]Department of Chemistry, Clemson University, Clemson, SC, USA [3]The Bent Creek Institute, The North Carolina Arboretum, Asheville, NC, USA

出　　处：《Natural Science》2016年第8期359-379,共22页自然科学期刊（英文）

摘　　要：Several polyphenolic compounds, including twelve flavonols and a variety of lower molecular weight compounds were found to diminish the effects of CuZnSOD on NMR relaxation of fluoride ion in a pH and concentration dependent manner. While we originally thought the effect arose from binding of the compounds to the enzyme active site, several lines of evidence indicated that active polyphenols reduced the paramagnetic copper(II) form of the enzyme to the diamagnetic copper(I) form, thereby giving false positive indications of enzyme inhibition in the NMR assay. First, docking experiments failed to provide a satisfactory explanation of the SAR. Second, effects on the enzyme’s EPR spectrum indicated that catechols could bind the active site copper leading to enzyme reduction. Third, while these reactions did not proceed to completion in aerobic solution, they did so under inert atmosphere. Fourth, experiments employing superoxide producing compounds demonstrated that loss of NMR activity did not prevent the enzyme from redox cycling. Thus, while the polyphenols appeared to inhibit the enzyme in the NMR assay, the compounds did not inhibit the enzyme’s reactions with superoxide.Several polyphenolic compounds, including twelve flavonols and a variety of lower molecular weight compounds were found to diminish the effects of CuZnSOD on NMR relaxation of fluoride ion in a pH and concentration dependent manner. While we originally thought the effect arose from binding of the compounds to the enzyme active site, several lines of evidence indicated that active polyphenols reduced the paramagnetic copper(II) form of the enzyme to the diamagnetic copper(I) form, thereby giving false positive indications of enzyme inhibition in the NMR assay. First, docking experiments failed to provide a satisfactory explanation of the SAR. Second, effects on the enzyme’s EPR spectrum indicated that catechols could bind the active site copper leading to enzyme reduction. Third, while these reactions did not proceed to completion in aerobic solution, they did so under inert atmosphere. Fourth, experiments employing superoxide producing compounds demonstrated that loss of NMR activity did not prevent the enzyme from redox cycling. Thus, while the polyphenols appeared to inhibit the enzyme in the NMR assay, the compounds did not inhibit the enzyme’s reactions with superoxide.

关 键 词：Paramagnetic NMR SOD POLYPHENOL FLAVONOL 

分 类 号：O62[理学—有机化学]