%A Ragauskas,Arthur %A Pu,Yunqiao %A Samuel,Reichel %A Jiang,Nan %A Fu,Chunxiang %A Wang,Zeng-Yu %D 2014 %J Frontiers in Energy Research %C %F %G English %K Switchgrass,COMT transgenic,Lignin,NMR,GPC,Molecular Weight %Q %R 10.3389/fenrg.2013.00014 %W %L %M %P %7 %8 2014-January-20 %9 Original Research %+ Prof Arthur Ragauskas,Georgia Institute of Technology,School of Chemistry and Biochemistry,500 10th St., NW,Atlanta,30332,GA,United States,aragausk@utk.edu %# %! Lignin in COMT Down-regulated Switchgrass %* %< %T Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass %U https://www.frontiersin.org/articles/10.3389/fenrg.2013.00014 %V 1 %0 JOURNAL ARTICLE %@ 2296-598X %X This study examined the chemical structural characteristics of cellulolytic enzyme lignin isolated from switchgrass focusing on comparisons between wild-type control and caffeic acid 3-O-methyltransferase (COMT) down-regulated transgenic line. Nuclear magnetic resonance techniques including 13C, 31P, and two-dimensional 13C-1H heteronuclear single quantum coherence as well as gel permeation chromatography were employed. Compared to the wild-type, the COMT down-regulated transgenic switchgrass lignin demonstrated a decrease in syringyl (S):guaiacyl (G) ratio and p-coumarate:ferulate ratio, an increase in relative abundance of phenylcoumaran unit, and a comparable content of total free phenolic OH groups along with formation of benzodioxane unit. In addition, COMT down-regulation had no significant effects on the lignin molecular weights during its biosynthesis process.