Category Archives: Biomass Recalcitrance

Molecular modeling

Molecular dynamics and molecular mechanics calculations have been used extensively to examine cellulose, often giving unexpected results. Because of inadequate information con­tained in fiber diffraction patterns noted above, all models for cellulose have been developed to some extent through modeling wherein constraints are imposed on the solution to com­plement inadequate data sets. The constraints most often used are dimensions of […]

Read more

CCR, CAD, F5H, and COMT downregulation/mutation, and the enigma of monolignol radical generation

Since the early 1930s or so, there have been a number of reports indicating that various agronomically important plant species, i. e., maize (Zea mays), sorghum (Sorghum bicolor), and pearl millet (Pennisetum glaucum), can produce so-called brown-midrib mutants. The maize mutants (bm1-bm4) were spontaneous mutations (58-60) and were later shown to have lower lignin contents than wild-type lines (62), whereas […]

Read more

Force fields

From the discussion above it should be obvious that the accuracy of any molecular mechanics method is entirely dependent on the quality of the parameterization used. In theory one could parameterize specifically for each simulation that is to be run but this would be extremely time-consuming and would also make the parameters non-transferable. Instead, in order to preserve the transferability […]

Read more

Xyloglucanases

Xyloglucan is one of the major hemicellulose polymers in growing primary cell walls of various plant species. Due to analytical problems, it has been difficult to differentiate it from cellulose and xylan. Xyloglucan is closely associated with cellulose microfibrils via hydrogen bonding, thus providing the load-bearing network of the cell wall, which protects the cell wall from collapsing due to […]

Read more

Cellulase regulation

Regulation of cellulase synthesis by C. thermocellum is an important feature of the physiology of this microorganism, particularly in light of the substantial investment of ATP that cellulase synthesis represents (34,35). Johnson and coworkers (36) reported that true cellulase activity (i. e., degradation of crystalline cellulose) synthesis was markedly repressed by cellobiose. mRNAs corresponding to endoglucanases CelA, CelF, and CelD […]

Read more

The myo-inositol pathway

In plants, the first step in myo-inositol synthesis is the cyclization of d-G1c-6-P to myo — inositol-1-P (Ino-1P) by lL-myo-inositol 1-phosphate synthase. In Arabidopsis, two func­tional isoforms were reported, At4g39800 and At2g22240 (454). The second step involves dephosphorylation of Inol-P to myo-inositol by myo-inositol monophosphatase (IMPase; EC 3.1.3.25) (455). Distinct multiple but highly conserved IMPase isoforms are found in each […]

Read more

Metabolic flux analyses and transcriptional profiling in the monolignol pathway

These analyses have been most useful in predicting the outcome of various manipulations in the lignin-forming pathway. That is, previous studies, whereby monolignol 1 and 3 formation could be induced in loblolly pine (Pinus taeda) cell suspension cultures, enabled us to gain important insights into factors controlling metabolic flux to both p-coumaryl (1) and coniferyl (3) alcohols (34, 35). Thus, […]

Read more

Transcriptional control over secondary wall fiber formation: ramifications for lignification and vascular integrity

One of the most exciting discoveries in recent years, as regards cell wall formation, is that of the roles of two transcription factors [SND1 (also called NST3) and NST1]. These are responsible for (secondary wall formation) in fibers of Arabidopsis (198, 199), and are specifically expressed in interfascicular fibers and xylary fibers as shown using the GUS reporter gene strategy […]

Read more
1 2 3 4 30