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1.
Bioresour Technol ; 135: 58-66, 2013 May.
Article in English | MEDLINE | ID: mdl-23186666

ABSTRACT

Wheat straw fractionation by ethanol organosolv was studied as pretreatment for enzymatic cellulose hydrolysis. A parametric study focusing on temperature, reaction time, acid catalyst dose, solvent concentration, and particle size was performed to determine their influence on delignification, xylan hydrolysis, and enzymatic cellulose digestibility. Major process parameters were found to be temperature, ethanol concentration, and acid dose. Optimisation of the process towards enzymatic digestibility resulted in a maximum glucose yield of 86% without the use of a catalyst (lignin yield 84%, organosolv at 210 °C, 50% w/w aqueous EtOH). Using 30 mM H2SO4 as catalyst resulted in similar glucose and lignin yields at a lower temperature (190 °C, 60% w/w aqueous EtOH). Lowering the pretreatment temperature by using an acid catalyst substantially improved the yield of the hemicellulose derivatives xylose and furfural. A systematic approach in pretreatment optimisation is vital for development of efficient lignocellulosic biorefineries.


Subject(s)
Cellulase/biosynthesis , Cellulose/metabolism , Ethanol/pharmacology , Lignin/biosynthesis , Solvents/pharmacology , Triticum/drug effects , Waste Products/analysis , Biocatalysis/drug effects , Biomass , Chemical Fractionation , Hydrogen-Ion Concentration/drug effects , Particle Size , Sulfuric Acids/pharmacology , Temperature , Time Factors
2.
Carbohydr Res ; 346(8): 1005-12, 2011 Jun 01.
Article in English | MEDLINE | ID: mdl-21486666

ABSTRACT

To enable enzymatic coupling of saccharides to proteins, several di- and trisaccharides were hydroxy-arylated using anhydrous transesterification with methyl 3-(4-hydroxyphenyl)propionate, catalyzed by potassium carbonate. This transesterification resulted in the attachment of up to 3 hydroxy-aryl units per oligosaccharide molecule, with the monosubstituted product being by far the most abundant. The alkaline reaction conditions, however, resulted in a partial breakdown of reducing sugars. This breakdown could easily be bypassed by a preceding sugar reduction step converting them to polyols. Hydroxy-arylated products were purified by using solid phase extraction, based on the number of hydroxy-aryl moieties attached. Monohydroxy-arylated saccharose was subsequently linked to a tyrosine-containing tripeptide using horseradish peroxidase, as monitored by LC-MS(n). This proof of principle for peptide and protein glycation with a range of possible saccharides and glycosidic polyols can lead to products with unique new properties.


Subject(s)
Glycosides/chemistry , Glycosides/chemical synthesis , Horseradish Peroxidase/metabolism , Hydroxides/chemistry , Oligopeptides/metabolism , Oligosaccharides/metabolism , Polymers/chemistry , Tyrosine/chemistry , Biomimetic Materials/chemistry , Biomimetic Materials/metabolism , Carbohydrate Sequence , Catalase/metabolism , Esterification , Esters , Glycosylation , Oligopeptides/chemistry , Oligosaccharides/chemical synthesis , Oligosaccharides/chemistry , Oxidation-Reduction , Phenols/chemistry , Tyrosine/metabolism
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