Peroxidases Bound to the Growing Lignin Polymer Produce Natural Like Extracellular Lignin in a Cell Culture of Norway Spruce.

Lignin, an important component of plant cell walls, is a polymer of monolignols derived from the phenylpropanoid pathway. Monolignols are oxidized in the cell wall by oxidative enzymes (peroxidases and/or laccases) to radicals, which then couple with the growing lignin polymer. We have investigated the characteristics of the polymerization reaction by producing lignin polymers using different oxidative enzymes and analyzing the structures formed with NMR.

Characterization of basic p-coumaryl and coniferyl alcohol oxidizing peroxidases from a lignin-forming Picea abies suspension culture.

A Norway spruce (Picea abies) tissue culture line that produces extracellular lignin into the culture medium has been used as a model system to study the enzymes involved in lignin polymerization. We report here the purification of two highly basic culture medium peroxidases, PAPX4 and PAPX5, and isolation of the corresponding cDNAs. Both isoforms had high affinity to monolignols with apparent K(m) values in microM range.

Developmental lignification and seasonal variation in beta-glucosidase and peroxidase activities in xylem of Scots pine, Norway spruce and silver birch.

We examined the relationship between beta-glucosidase and peroxidase activities and xylem lignification in the stems of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.

Quantitative 2D HSQC (Q-HSQC) via suppression of J-dependence of polarization transfer in NMR spectroscopy: application to wood lignin.

A quantitative method to record (1)H-(13)C correlation NMR spectra (Q-HSQC) is presented. The suppression of (1)J(CH)-dependence is achieved by modulating the polarization transfer delays of HSQC. In addition, the effect of homonuclear couplings, as well as relaxation during the pulse sequence are discussed.

Analysis of technical lignins by two- and three-dimensional NMR spectroscopy.

Modern multidimensional NMR spectroscopic methods were applied to investigate the effects of kraft pulping and oxygen delignification on lignin side-chain structures. In addition to the two-dimensional HSQC measurements, the three-dimensional HSQC-TOCSY technique was utilized to elucidate the (1)H-(1)H and (1)H-(13)C correlations of individual spin systems and thus indicate a certain lignin side-chain structure. Unlike earlier, nonlabeled samples were used for 3D measurements.