Lignin chemistry?past, present and future

Adler, Erich

doi:10.1007/bf00365615

Cited by 1,564 publications

(974 citation statements)

References 126 publications

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“…In native lignin macromolecules, roughly half of the linkages are of the 8-0-4' alkyl aryl ether type in lignified plant cell walls (36). Since dehydrogenative polymerization of monolignols in vitro does not yield the same relative proportions of interunit linkages as observed in native biopolymers, certain facets of the macromolecular assembly processes in vivo differ significantly from the dehydrogenative polymerization of monolignols in open solution.…”

Section: Dehydrogenative Polymerization Of Monolignols To Ligninsmentioning

confidence: 95%

“…That is, natural lignins mainly embody 8-0-4' (>50%) and dehydrodiconiferyl alcohol (-10%) substructures, together with a variety of other linkages present in relatively low abundance. This has been established not only through degradative analyses (36), but also by specific in situ carbon-13 labeling, which was initially applied in order to study lignin biosynthesis (37,38). There is, therefore, a marked contrast between lignin structures in vivo and those of the so-called monolignol dehydropolymerisates produced in vitro.…”

Section: Brief Historical Development Of Ideasmentioning

confidence: 99%

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Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lewis

Davin

Sarkanen

1998

ACS Symposium Series

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Before 1996, the framework within which lignin biosynthesis was understood at the molecular level had not fundamentally changed for 4 decades. During the same period nothing at all had been explicitly proposed about the mechanistic basis for lignan formation in vivo. The associated deficit in plant biochemistry was not minor: lignins and lignans together account for roughly 30% of the organic carbon in vascular plants. On the other hand, the biochemical transformations in phenylpropanoid metabolism leading, via the shikimate-chorismate pathway through phenylalanine or tyrosine, to the so-called monolignols (namely, the monomeric lignin/lignan precursors) came to be reasonably well documented. Indeed, attention has more recently been drawn to the identification of de facto rate-limiting steps in the various metabolic segments of the pathway as potential control-points for biotechnological manipulation. The most curious characteristic usually attributed to the lignin/lignan biosynthetic pathway is that the monolignol-derived radical coupling processes leading to lignans are regio-and stereospecific, whereas those resulting in lignin macromolecules ostensibly are not. Now that the molecular basis for the dehydrogenative dimerization of monolignols to lignans has been unraveled, however, it appears likely that an analogous mechanism may be operative in the dehydrogenative polymerization of monolignols to lignins. The investigation of this possibility has indeed become a central concern in the field of lignin biosynthesis.It has been almost three decades (7) since a comprehensive attempt had been made to summarize and evaluate contending views about lignin biosynthesis. Accordingly, the present volume draws together the current, yet conceptually vastly differing, ideas about how lignin composition and structure are established in living plants. It differs from all prior contributions, not only in introducing fresh evidence to support a compelling new paradigm that seeks to understand how lignin structure is established in vivo, but also in including lignan biosynthesis for comparative purposes. Indeed it appears that the first committed step in lignan biosynthesis bears an important relationship to the manner in which the configurations of lignins are specified in vivo.

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Section: Dehydrogenative Polymerization Of Monolignols To Ligninsmentioning

confidence: 95%

Section: Brief Historical Development Of Ideasmentioning

confidence: 99%

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lewis

Davin

Sarkanen

1998

ACS Symposium Series

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“…This also implies that calculations of the average number of water molecules per sorption site in wood cell wall polymers do not express anything about the actual distribution of water molecules between sorption sites, unless only accessible sites are included in the estimation. Formula units derived from wood-polymer models from (a) to (b) (Sjöström 1993), (c) (Adler 1977), (d) (Sakakibara 1980) and (e) (Reid 1995) f only 33 % of the cellulose OH-groups are accessible to water. This gives a water accessible OH concentration of in situ cellulose of 6.1 mmol/g g R = CH 3 CO or H Wood Sci Technol (2013) 47:141-161 145 A number of studies have employed different variants of LFNMR relaxation experiments in an attempt to identify the states of water present in wood and other ligno-cellulosic materials.…”

Section: States Of Water In Woodmentioning

confidence: 99%

A critical discussion of the physics of wood–water interactions

et al. 2012

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This paper reviews recent findings on wood-water interaction and puts them into context of established knowledge in the field. Several new findings challenge prevalent theories and are critically discussed in an attempt to advance current knowledge and highlight gaps. The focus of this review is put on water in the broadest concept of wood products, that is, the living tree is not considered. Moreover, the review covers the basic wood-water relation, states and transitions. Secondary effects such as the ability of water to alter physical properties of wood are only discussed in cases where there is an influence on state and/or transition.

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“…1 However, very little is known about the natural variation of lignin content and its compositional traits in the wood of trees 2 despite the fact that 15-35% of it consists of lignin. Nevertheless, its function is essential: lignin is required for adequate retainment of water in the vascular system, for mechanical strength as the binding agent for the cellulose microfibril sheaths, and for resistance to insects and pathogens.…”

Section: Introductionmentioning

confidence: 99%

Propensity of Lignin to Associate: Light Scattering Photometry Study with Native Lignins

et al. 2008

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Many studies of lignins in solution invoke association and aggregation phenomena to explain their solution behavior (e.g., reprecipitation onto pulp fibers, condensation, etc.). Following their colloidal (apparent) molecular weights in solution as a function of time allows us to explore observable dissociation phenomena. These measurements were carried out using multiple angle laser light scattering (MALLS) photometry in the static mode. The challenges and opportunities of measuring the specific refractive index increment (dn/dC) of lignin solutions and determining the kinetics of the dissociation process were thus investigated. Hardwood and softwood representative lignins were isolated, and method for their full dissolution in THF was further developed, which then lead to accurate dn/dC values being obtained as a function of time. When coupled to additional work using light scattering static measurements and Zimm plots for the same solutions, this effort offers insight into the aggregation and ensuing dissociative events that operate within the lignin macromolecules.

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Lignin chemistry?past, present and future

Cited by 1,564 publications

References 126 publications

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

Lignin and Lignan Biosynthesis: Distinctions and Reconciliations

A critical discussion of the physics of wood–water interactions

Propensity of Lignin to Associate: Light Scattering Photometry Study with Native Lignins

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