Type of Document Master's Thesis Author Eberhardt, Thomas Leonard URN etd-04122010-083702 Title Studies on lignin biosynthesis and structure Degree Master of Science Department Forest Products Advisory Committee
Advisor Name Title Lewis, Norman G. Committee Chair Glasser, Wolfgang G. Committee Member Ifju, Geza Committee Member Keywords
Date of Defense 1988-02-15 Availability restricted Abstract
Beech (Fagus grand1folia Ehrh.> bark contains appreciable quantities of Z- (cis) con1feryl and Z-s1napyl alcohols and not the corresponding E- (trans) alcohols. Previous rad1otracer experiments suggested that the Z-coniferyl alcohol in beech bark is formed by isomerization of E-coniferyl alcohol which proceeds either directly or through the corresponding aldehydes. In the work conducted in this thesis, is has been found that crude cinnamy1 alcohol dehydrogenase isolated from beech bark shows a strong substrate preference for E-coniferyl alcohol (as opposed to Z-coniferyl alcohol) thereby suggesting that the E to Z isomerization described occurs directly at the alcohol level.
Administration of (2-14C) ferul1c acid to feland wheat (Triticum aest1yum L.) over extended durations (21 days) and subsequent isolation of the lignin from the root tissue as its acetal derivative demonstrated the incorporation of the labelled feru1ic acid into the lignin component of the tissue. Through sim1lar administrations of (1-13C, 2-13C and 3-13C) ferul1c acid and subsequent analysis of the root tissues by solid state 13C nuclear magnetic resonance (NMR) spectroscopy, it was possible to determine the bonding patterns of lignin in situ. The lignin component of each 13C feru1ic acid enriched root tissue was then isolated as its acetal derivative and analyzed by solution state 13C NMR.
Through comparison it was shown that the enhanced resonances observed in the solution state 13C NMR spectra of the 13C ferulic acid enriched acetal lignins corresponded to the enhanced resonances in the respective spectra of the intact root tissues. This indicated that minimal changes to the lignin bonding patterns occurred during the isolation procedure. The dominant presence of 13C NMR resonances corresponding to hydroxycinnamic acid functionalities in the solid and solution state NMR spectra demonstrates the important role of hydroxyc1nnamic acids in wheat root lignin. However, no evidence of the formation of dimers such as 4,4'-dihydroxytruxillic acid was noted. Thus, such structures do not represent an important bonding pattern in wheat root lignin.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access LD5655.V855_1988.E347.pdf 2.93 Mb 00:13:34 00:06:58 00:06:06 00:03:03 00:00:15next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.