93601-73-1

Ionic liquids (ILs) have emerged as an alternative to conventional organic media due to their high thermal and chemical stability, negligible vapour pressure, non-flammability and easy recycling. In this context, this work assesses the catalytic activity of a β-galactosidase from Bacillus circulans ATCC 31382 (β-Gal-3-NTag) in the synthesis of β-(1→3)-galactosides using different ILs. A noticeably increase in activity, retaining total regioselectivity was found in the synthetic behaviour of B. circulans β-galactosidase in ILs as co-solvents and using a 1:5 molar ratio of donor (pNP-β-Gal):acceptor (GlcNAc or GalNac). Yields up to 97% of β-(1→3) with different ILs were found. These reactions take place without noticeable hydrolytic activity and with total regioselectivity, representing a considerable improvement over the use of aqueous buffer or conventional organic solvents. Furthermore, reaction scaling up and IL recovery and recycling are feasible without losing catalytic action. Molecular modelling studies performed predict a three-dimensional interaction at the active centre between the acceptor and the water-IL mixture, which could explain the results obtained.

Glycosyl azides are shown to be efficient donors for β-galactosidases, β-glucosidases and α mannosidases. Only α-galactosidases do not cleave the respective glycosyl azide 1 and, moreover, they exhibit competitive inhibition (especially α-galactosidase fr

The invention provides a particle comprising fibrinogen bound on the surface of an albumin matrix, wherein said particle is capable of coaggregation with platelet, and of aggregation in a solution containing soluble fibrinogen at a concentration of soluble fibrinogen not capable by it self of formation of a clot upon activation by thrombin.

We examined the effect as donors of three aryl β-D-galactosides (i.e. p-nitrophenyl β-D-galactopyranoside, o-nitrophenyl β-D-galactopyranoside and phenyl β-D-galactopyranoside) on the regioselectivity and the yield of the synthesis of N-acetyllactosamine obtained from the transglycosylation reaction catalyzed by a crude preparation of β-D-galactosidase from Bacillus circulans at 25°C, 37°C and 55°C, respectively. Using p-nitrophenyl β-D-galactopyranoside the reaction results were fully regiospecific at all the temperatures considered: the maximum molar yield (74%) was obtained at an incubation temperature of 55°C Using o-nitrophenyl β-D-galactopyranoside as the donor the reaction was still highly regioselective and the maximum molar yield (50%) was achieved at an incubation temperature also of 55°C. Using phenyl β-D-galactopyranoside transglycolytic products appear only at an incubation temperature of 55°C but at very low molar yield (about 14%) and lower regioselectivity.

Albumin particles in the nanometer and micrometer size range in an aqueous suspension are rendered stable against resolubilization without the aid of a crosslinking agent and without denaturation, by the incorporation of a stabilizing agent in the particle composition. Particles which are primarily albumin in the nanometer and micrometer size range in an aqueous suspension are rendered stable against resolublization by the incorporation of a reducing agent, oxidizing agent, hydrogen-accepting molecule, high molecular weight polymer, sulfur-containing ring compound or combinations thereof.

β-Galactosidase activities from the recombinant thermophilic CLONEZYME(TM) glycosidase library were screened at 70°C for catalysis of a transgalactosylation from o-nitrophenyl-β-galactopyranoside to N-acetylglucosamine. Three thermophilic glycosidases (Gly001-06, -07 and -09) were found to produce predominantly the β(1-4)-linked isomer, Gal β(1-4)GlcNAc with up to 61% yield and less than 10% of the hydrolysis side reaction product. Thus, commercial recombinant thermophilic enzyme libraries constitute a novel class of biocatalysts for preparative organic synthesis.

Albumin particles in the nanometer and micrometer size range in an aqueous suspension are rendered stable against resolubilization without the aid of a crosslinking agent and without denaturation, by the incorporation of hemoglobin in the particle composition. Particles which are primarily hemoglobin in the nanometer and micrometer size range in an aqueous suspension are rendered stable against aggregation by the incorporation of either albumin, surface active agents or gelatin.

The use of β-galactosidases from five different sources in syntheses through transglycosylation leads to 3-O-methyl allolactose, N-acetyllactosamine, N-acetylallolactosamine and Gal(β1-6)Gal. The yield and distribution of products depends on the source of the enzyme and on the reaction conditions, viz. the nature of added organic co-solvent. Yields of 3-O-methyl allolactose (47%), Gal(β1-6)Gal (6%), N-acetylallolactosamine (30%) were obtained in aqueous buffer with β-galactosidase from E. coli. The same reactions occurred at much lower rates in the presence of water-miscible organic solvents. With β-galactosidases from K. fragilis and A. oryzae, however, the synthesis of the above disaccharides occurred only in the presence of organic solvent (> 60% v/v triethyl phosphate, trimethyl phosphate or tetraglyme) but not in aqueous buffer solution. β-galactosidases from D. pneumoniae and B. circulans in systems incorporating organic solvent produced 3-O-methyl allolactose and N-acetyllactosamine in yields of 30-40%. The direct separation of oligosaccharides on a preparative scale can be achieved by Ca2+-ligand exchange chromatography. Ultrafiltration was also used for the efficient recycling of enzymes.

D-Galactosyl disaccharides have been synthesized by utilizing the reversed hydrolysis activity of β-D-galactosidases from E. coli and from A. oryzae, respectively.In order to shift the equilibrium towards the formation of disaccharide, solutions of monosaccharides were circulated through columns of immobilized β-D-galactosidase and activated carbon in series.After 24 h, the disaccharides were eluted with aqueous 50 percent ethanol from the column of activated carbon and analyzed by h.p.l.c. and 13C-n.m.r. spectroscopy.In this way, β-D-galactosyl-D-glucose, β-D-galactosyl-2-acetamido-2-deoxy-D-glucose, and β-D-galactosyl-D-fructose were produced in yields of 6.0, 16.0, and 11.3 percent, respectively, when the immobilized β-D-galactosidase from E. coli was used.The possible mechanism of the synthesis of the disaccharides is discussed.

Acetalation of o-nitrophenyl 2-acetamido-2-deoxy-alpha-D-galactopyranoside with p-methoxybenzaldehyde-zinc chloride complex afforded the 4,6-O-(p-methoxybenzylidene) derivative (1). Acetylation of 1 with pyridine-acetic anhydride gave the crystalline mono

As a route for forming spacers of differing functionality for linking oligosaccharides to carrier molecules, the allyl glycosides of β-D-Glc->β-D-GlcNAc disaccharides having β-D-(1->3) and β-D-(1->6) linkages were prepared.The aglycon could be removed dir