Mass spectrometry in the biosynthetic and structural investigation of lignins

Abstract

Lignin, a resistant cell-wall constituent of all vascular plants that consists of ether and carbon-linked methoxyphenols, is still far from being structurally described in detail. The main problem in its structural elucidation is the difficulty of isolating lignin from other wood components without damaging lignin itself. Furthermore, the high number and variegated forms of linkages that occur between the monomeric units and the chemical resistance of certain ether bonds limit the extent to which analytical and degradation procedures can be used to elucidate the lignin structure. Most of our present knowledge about the molecular structure of lignin is based on the analysis of monomers, dimers or, at the most, tetramers of degraded isolated lignins. Mass spectrometry (MS), which offers advantages in terms of speed, specificity, and sensitivity, has revealed to be a very powerful technique in the structural elucidation of lignins, in combination with the great number of chemical and thermal degradation methods available in the study of lignin. Moreover, the recent development of new ionization techniques in MS-electrospray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-MS-has provided new possibilities to also analyze the undegraded lignin macromolecule.

A Novel Allosteric Pathway of Thrombin Inhibition

“…Although heparin possesses a hydrophilic polysaccharide scaffold, sulfated DHPs are based on the hydrophobic "lignin" scaffold. Natural lignins are plant constituents made up of phenylpropanoid monomers that offer the capability of introducing a limited number of sulfate groups (31,32). We reasoned that introducing carboxylate groups in the basic lignin scaffold will offer an avenue in the future of being able to introduce oral bioavailability through the traditional carboxylic acid ester-based pro-drug approach.…”

Lignin Biosynthesis and Structure

“…During each coupling reaction, two radicals are "consumed" (in a so-called "termination reaction") as each single electron contributes to the newly formed bond, making this type of radical polymerization intrinsically different from the radical chain reactions that occur in the polymerization of several industrial polymers, such as polyethylene, polypropylene, and polystyrene. The average length of a linear lignin chain in poplar is estimated to be between 13 and 20 units (Reale et al, 2004;Stewart et al, 2009).…”

Biomass Pyrolysis Kinetics: A Review of Molecular-Scale Modeling Contributions

“…Since 2000, however, pyrolysis of whole biomass, cellulose and lignin has been a fastmoving field of research, spawning extensive reviews, every 10 months (inclusive of the recent papers by Vinu and Broadbelt, 2012, Lede, 2012and and Burnham, Zhou and Broadbelt, 2015 on the average in an effort to inform the research community and keep-up with the pace of advances. In addition to the earlier reviews on cellulose already mentioned, the following papers, listed chronologically, chronical the advances made in the 15 year period from 2000 to 2015 (Anital Jr, 1985;Sinha, et al, 2000;Bridgwater and Peacocke, 2000;Amen-Chen, Pakdel and Roy, 2001;Czernick and Bridgwater, 2004;Reale, et al, 2004;Branca, Albano and Di Blasi, 2005;Mohan, Pittman and Steele, 2006;Prakash and Karunanithi, 2008;Venderbosch and Prins, 2010;Slutter, et al, 2010;White, Catallo and Legendre, 2011;Pandey and Kim, 2011;Bridgwater, 2012;and Shen, et al, 2015). Short of the work by Vinu andShen, et al, 2015, even the most recent reviews hardly mention the already large and rapidly growing body of literature on molecular-based modeling studies that are now a mainstream part of the effort to elucidate the complex process of lignocellulosic biomass pyrolysis.…”

“…In a unique review, Reale et al (2004) review works associated with the application of mass spectroscopy to study lignin. This review is equally of value -though at this point somewhat dated since 12 years have passed since its publication -for the study of whole biomass, cellulose and hemicellulose depolymerization.…”