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  • supersaturated solutions  (3)
  • affinity purification  (1)
  • biocatalysis nonaqueous  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Enzymatic catalysis in heterogenous mixtures of substrates: The role of the liquid phase and the effects of “Adjuvants” (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1016-1023 
    Details
    ISSN: 0006-3592
    Keywords: biocatalysis nonaqueous ; peptide synthesis ; eutectic mixtures ; subtilisin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physicochemical mechanism of protease-catalyzed peptide synthesis in heterogenous etuectic mixtures of substrates has been examined by a combination of microscopic techniques. Using a number of model reactions of dipeptide amide synthesis, it was determined that liquid phase catalysis was mostly, if not exclusively, responsible for the observed conversion of substrates. Furthermore, the formation of liquid or semiliquid eutectics was an important requirement for the occurrence of those reactions where both substrates were solids in the pure state. The addition of small quantities of hydrophilic solvents (adjuvants) often resulted in significat improvements in the rates and yields of the reactions. This was due to the ability of these adjuvants to promote the formation of eutectics, thereby increasing the proportion, as well as affecting the composition the properties, as well as affecting the composition and properties of the liquid phase. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260431104
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  • 2
    Electronic Resource
    Electronic Resource
    Regioselective synthesis of ethoxylated glycoside esters using β-glucosidase in supersaturated solutions and lipases in organic solvents (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 747-753 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; glycosidases ; lipases ; supersaturated solutions ; organic solvents ; esterification ; glycosides ; ethyleneglycol ; sugar fatty acid esters ; surfactants ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three ethoxylated glycosides, tetraethylene glycol β-D-glucoside, tetraethylene glycol β-D-xyloside, and methoxy triethyleneglycol β-D-glucoside, were prepared via almond β-glucoside-catalyzed (trans)glycosylation carried out in supersaturated solutions of glucose or p-nitrophenyl β-D-xyloside and the respective polyethylene glycols. The products were isolated and further modified by enzymatic esterification with Candida antarctica and Mucor miehei lipases. The latter enzyme showed a much greater selectivity for the primary hydroxyl group on the polyethylene glycol chain of the glucoside substrate, thus enabling us to obtain exclusively the corresponding monoester, ω-O-oleoyl tetraethylene glycol β-D-glucoside. Novozyme was used for the preparative synthesis of two other monoesters, 6-O-oleoyl (methoxy triethyleneglycol) β-D-glucoside and ω-O-oleoyl tetraethylene glycol β-D-xyloside. Two diesters, di-oleoyl tetraethylene glycol β-D-glucoside and tetraethylene-bis(6-0-oleoyl glucoside) were also synthesized in good yields using this lipase. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:747-753, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymatic transformations in supersaturated substrate solutions: I. A general study with glycosidases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 190-196 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; glycosidases ; glycosides ; supersaturated solutions ; plasticizers ; ethylene glycol ; glycerol ; acrylates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The results of an initial study of enzymatic catalysis in metastable supersaturated solutions of carbohydrates are presented. It has been shown that such solutions, formed in the presence of small amounts of water and alcohol as plasticizers, are sufficiently stable under ambient conditions to enable enzymatic transformations of substrates. A partial phase diagram for a system consisting of glucose, water, and (poly)ethylene glycol was constructed to identify the regions which are most suitable for biotransformations. It was confirmed that the glass transition in this system occurred below the reaction temperature at any given composition of the constituent components. Several glycosidases were found to be catalytically active in this medium and the activity of β-glucosidase from almond was determined at several compositions of the reaction mixture and related to the corresponding regions of the phase diagram. The synthetic utility of the system was illustrated by glucosylation of several α,ω-alkyldiols, short-chain polyethylene glycols, and hydroxyalkyl and glyceryl monoacrylates. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 190-196, 1998.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Enzymatic transformations in supersaturated substrate solutions: II. Synthesis of disaccharides via transglycosylation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 197-203 
    Details
    ISSN: 0006-3592
    Keywords: enzymes ; glycosidases ; transglycosylations ; supersaturated solutions ; glycosides ; disaccharides ; synthesis ; regioselectivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymatic transglycosylation in supersaturated solutions of substrates was investigated using crude glycosidase preparations from barley, snail, and coffee beans. It was shown that the use of supersaturated glycoside solutions as media for transglycosylation reactions offers considerable advantages over conventional aqueous systems. These advantages include higher yields, more efficient use of the donor glycosides and improved volumetric productivity, especially in the case of poorly water-soluble substrates. The regioselectivity of the glycosylation was not significantly affected by high concentrations of acceptor glycosides. It was also shown that the regioselectivity of transfer could be directed towards secondary hydroxyl groups by the use of methyl 6-O-acetyl-α-galactopyranoside as acceptor. The value of these approaches was demonstrated by the synthesis of methyl 3- and 4-O-β-D-galactopyranosyl-α-D-galactopyranosides and methyl 3-O-β-D-galactopyranosyl-α-L-fucopyranoside on a preparative scale. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 197-203, 1998.
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    The synthesis of sub-micron magnetic particles and their use for preparative purification of proteins (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 419-424 
    Details
    ISSN: 0006-3592
    Keywords: magnetic beads ; polymer particles ; surface functionality ; affinity purification ; proteins ; trypsin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel one-step protocol for the preparation of sub-micron magnetic particles as small as 30 nm in diameter has been developed. The surface of the particles was functionalized with carboxyl groups (∼1 COOH per 15Å2) to facilitate the attachment of affinity ligands. The high surface area of the resulting beads, combined with the high density of functional groups on the surface, makes them ideally suited for the preparative purification of proteins as was demonstrated by the efficient isolation of trypsin (36 mg per gram of particles) from pancreatic extract. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 419-424, 1998.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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