Solubility of Softwood Hemicelluloses

It is demonstrated that the molecular solubility of softwood hemicelluloses is significantly influenced by pretreatment of the fibers, extraction, and downstream processing. To quantify these effects, four hemicellulose samples were extracted from different thermomechanical pulps of Norway spruce. The molecular solubility of the samples was characterized by size and molar mass distributions, and the morphology of the molecules was studied using high resolution microscopy techniques. All extracted samples were well dispersed in aqueous media creating transparent dispersions, but dynamic light scattering measurements showed that molecular solubility can only be achieved using specific pretreatments and extractions. The procedure yields acetylated galactoglucomannan (AcGGM)-rich hemicelluloses with an average molar mass of 21–35 kDa and a diameter up to 10 nm but also shows that water is a poor solvent for this sample since an association is detected as soon as the concentration is about 20 g/L. These associated hemicellulose dispersions are still absolutely clear on visual inspection, underlining the need for careful measurement when assessing the solubility of wood hemicelluloses

Data_Sheet_1_Crystal structure of the feruloyl esterase from Lentilactobacillus buchneri reveals a novel homodimeric state.PDF

Ferulic acid is a common constituent of the plant cell-wall matrix where it decorates and can crosslink mainly arabinoxylans to provide structural reinforcement. Microbial feruloyl esterases (FAEs) specialize in catalyzing hydrolysis of the ester bonds between phenolic acids and sugar residues in plant cell-wall polysaccharides such as arabinoxylan to release cinnamoyl compounds. Feruloyl esterases from lactic acid bacteria (LAB) have been highlighted as interesting enzymes for their potential applications in the food and pharmaceutical industries; however, there are few studies on the activity and structure of FAEs of LAB origin. Here, we report the crystal structure and biochemical characterization of a feruloyl esterase (LbFAE) from Lentilactobacillus buchneri, a LAB strain that has been used as a silage additive. The LbFAE structure was determined in the absence and presence of product (FA) and reveals a new type of homodimer association not previously observed for fungal or bacterial FAEs. The two subunits associate to restrict access to the active site such that only single FA chains attached to arabinoxylan can be accommodated, an arrangement that excludes access to FA cross-links between arabinoxylan chains. This narrow specificity is further corroborated by the observation that no FA dimers are produced, only FA, when feruloylated arabinoxylan is used as substrate. Docking of arabinofuranosyl-ferulate in the LbFAE structure highlights the restricted active site and lends further support to our hypothesis that LbFAE is specific for single FA side chains in arabinoxylan.</p

MOESM2 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 2: Figure S2. SEC profiles of KGMN and LBGN before and after enzymatic hydrolysis

MOESM1 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 1: Figure S1. Reducing sugar equivalents over time for enzyme reactions on SpGGM

MOESM5 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 5: Figure S5. Oligosaccharide product profiles from HPAEC-PAD analysis of 24-h hydrolysis of the chemically acetylated substrates KGMA and LBGA, compared with native KGMN and LBGN

MOESM3 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 3: Figure S3. Oligosaccharide product profiles obtained with HPAEC-PAD at three incubation times, with increasing concentrations of enzyme

MOESM5 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 5: Figure S5. Oligosaccharide product profiles from HPAEC-PAD analysis of 24-h hydrolysis of the chemically acetylated substrates KGMA and LBGA, compared with native KGMN and LBGN

MOESM6 of Mannanase hydrolysis of spruce galactoglucomannan focusing on the influence of acetylation on enzymatic mannan degradation

Additional file 6: Figure S6. Quantification of the M1-M4 oligosaccharides produced after 24 h hydrolysis reactions from the chemically acetylated substrates KGMA and LBGA, compared with native KGMN and LBGN

Toward Unimolecular Micelles with Tunable Dimensions Using Hyperbranched Dendritic-Linear Polymers

A library of amphiphilic, hyperbranched dendritic-linear polymers (HBDLPs) are successfully synthesized, and evaluated as potential unimolecular micelles. Hyperbranched macroinitiators (HBMI), extended with poly­(ethylene glycol) methacrylate (P­(OEGMA)), are afforded via a combination of self-condensing vinyl (co)­polymerization (SCV­(C)­P) and atom transfer radical polymerization (ATRP), providing a versatile two-step synthetic route. The HBDLP architecture and chain lengths are varied, and the effect on the nanoparticle (NP) stability and properties are evaluated. The HBDLPs form predominantly stable and spherical NPs, and the NP dimensions could be tailored by the HBDLP characteristics. The NPs formed are of high molecular weight, and their stability varies with the properties of the corresponding HBDLP. Too small dendritic segment, or too low degree of PEGylation, results to some extent in NP aggregation, while higher molecular weight HBDLPs, with a high amount of hydrophilic segments, appears to form discrete unimolecular micelles. The versatility of the platform is further demonstrated by the convenience of forming a HBDLP with a more complex, linear copolymer extension instead of P­(OEGMA)

Molecular Structural Differences between Type-2-Diabetic and Healthy Glycogen

Glycogen is a highly branched glucose polymer functioning as a glucose buffer in animals. Multiple-detector size exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis were used to examine the structure of undegraded native liver glycogen (both whole and enzymatically debranched) as a function of molecular size, isolated from the livers of healthy and db/db mice (the latter a type 2 diabetic model). Both the fully branched and debranched levels of glycogen structure showed fundamental differences between glycogen from healthy and db/db mice. Healthy glycogen had a greater population of large particles, with more α particles (tightly linked assemblages of smaller β particles) than glycogen from db/db mice. These structural differences suggest a new understanding of type 2 diabetes