Constitution and Biosynthesis of Lignin

ISBN-13: 9783540042747 / Angielski / Miękka / 1968 / 132 str.

Karl Freudenberg; A. C. Neish

Opis

Among terrestrial plants the vascular plants are the largest and the most con- spicuous. Because of the presence of lignified supporting and conducting tissues such as xylem, terrestrial vascular plants can develop large upright forms. Composed mainly of xylem tissue, the stems of trees are characterized by elongated cells with thickened walls, impregnated by lignin. Diagrams of xylem cells (vessels, tracheids and fibers) can be seen in textbooks of plant anatomy (e. g. ESAU, 1953). A cross section of xylem tissue is shown in the section of this volume written by Professor FREUDENBERG (Fig. 1, p. 98). In general the occurrence of lignin in the plant kingdom is associated with the presence of these cells which comprise xylem. Thus lignin is found in vascular plants such as lycopods, ferns, gymnosperms and angiosperms, whereas it is absent from simple plants such as fungi, and from all other organisms. The mosses are an exceptional group which do not have the cells characteristic of xylem tissue but which contain lignin-like materials. These "moss lignins" have been discussed by Professor FREUDENBERG in this volume, and some doubts have been expressed as to whether or not they are true lignins (FR. * pp. 113-114). Work on the chemistry of lignin indicates that it is a polymer derived from the phenylpropanoid compound, coniferyl alcohol and related alcohols.

Spis treści

Monomeric Intermediates in the Biosynthesis of Lignin.- I. Introduction.- II. Experimental Methods.- A. General Remarks.- B. Tracer Studies.- 1. Feeding of Precursors.- 2. Measurement of 14C-Incorporation into Lignin.- C. Enzyme Studies.- III. Biosynthesis of Aromatic Amino Acids in Plants.- A. Summary of Work with Bacterial Mutants.- B. Studies on Vascular Plants.- IV. Ring-substituted Cinnamic Acids as Intermediates in Lignification.- A. General Remarks.- B. Tracer Studies.- 1. Comparison of Precursors.- 2. Comparison of Species.- C. Enzyme Studies.- V. Cinnamyl-Alcohol Derivatives as Intermediates in Lignification.- VI. Compounds Biogenetically-Related to Lignin.- VII. Evolution of Lignification.- VIII. Summary.- IX. References.- The Constitution and Biosynthesis of Lignin.- I.- A. The Beginning.- B. Lignin Preparations and Their Isolation.- C. Lignin Derivatives and Their Preparation.- D. The Aromatic Nature of Lignin.- E. Other Observations.- 1. Liberation of Formaldehyde; search for C-Methyl.- 2. Oxidation to Vanillin and Allied Materials.- 3. Other Oxidation Products.- 4. Hydrogenation.- 5. Lignin and Alcohols.- F. The Elemental Analysis of Lignin and the Calculation of Its Composition.- 1. Introductory Remarks.- 2. Expression of Lignin Analyses.- 3. Recalculation of Analyses for Acetyllignin.- 4. Recalculation of Analyses for Methyllignin.- 5. Recalculation of Lignothioglycolic Acid.- G. Analytical Data on Lignin.- 1. Elemental Composition.- 2. Hydroxyl Estimation.- 3. Carbonyl Groups.- 4. Ether Oxygen and Oxygen Balance.- H. Early Approaches to the Constitution of Lignin.- II.- A. Degradation of Lignin to Methoxybenzenecarboxylic Acids and Other Products.- 1. Compounds of the Catechol (Veratrole) Series.- 2. Compounds of the Anisole Series.- 3. Compounds of the Trimethoxybenzene Series.- 4. Other Oxidation Products.- B. The Dehydrogenation of Coniferyl Alcohol.- 1. Introductory Remarks.- 2. Monolignols.- 3. Dilignols.- 4. Trilignols.- 5. Higher Oligolignols.- C. Linkage of Lignin with Carbohydrates.- D. Quinone Methides: Benzyl Aryl Ethers in Lignin; Hydrolysis Products.- E. Biochemical and Tracer Experiments.- 1. Biochemical Experiments and Other Observations.- 2. Tracer Experiments.- F. Schematic Model of the Constitution of Spruce Lignin.- G. Appraisal of the Schematic Formula for Spruce Lignin.- H. Other Proposals for Formulae.- I. Beech Lignin, Other Kinds of Lignin and the Concept of Lignin; Lignite and Humic Acid.- 1. Beech Lignin and Other Kinds of Lignin.- 2. The Concept of Lignin.- 3. Fossilized Wood (Lignite).- 4. Humic Substances.- K. Concluding Remark.- L. References.