1 introduction: immobilized enzymes: past, present ?· 1 introduction: immobilized enzymes: past,...

Download 1 Introduction: Immobilized Enzymes: Past, Present ?· 1 Introduction: Immobilized Enzymes: Past, Present…

Post on 11-Aug-2018

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 1Introduction: Immobilized Enzymes: Past, Present and Prospects

    1.1Introduction

    Since the second half of the last century, numerous efforts have been devoted tothe development of insoluble immobilized enzymes for a variety of applications [2];these applications can clearly benefit from use of the immobilized enzymes ratherthan the soluble counterparts, for instance as reusable heterogeneous biocatalysts,with the aim of reducing production costs by efficient recycling and control of theprocess [3, 4], as stable and reusable devices for analytical and medical applica-tions [511], as selective adsorbents for purification of proteins and enzymes [12],as fundamental tools for solid-phase protein chemistry [13, 14] and as effective mi-crodevices for controlled release of protein drugs [15] (Scheme 1.1).

    1

    Carrier-bound Immobilized Enzymes: Principles, Application and Design. Linqiu CaoCopyright 2005 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimISBN: 3-527-31232-3

    Scheme 1.1 Range of application of immobilized enzymes.

    However, whatever the nature of an immobilized enzyme and no matter how itis prepared, any immobilized enzyme, by definition, must comprise two essentialfunctions, namely the non-catalytic functions (NCF) that are designed to aid separ-ation (e.g. isolation of catalysts from the application environment, reuse of the cat-alysts and control of the process) and the catalytic functions (CF) that are designedto convert the target compounds (or substrates) within the time and space desired(Scheme 1.2).

    NCF are strongly connected with the physical and chemical nature of the non-catalytic part of the immobilized enzymes, especially the geometric properties, e.g.the shape, size, thickness, and length of the selected carrier, whereas the CF arelinked to the catalytic properties, for example activity, selectivity, and stability, pH

    Verwendete Mac Distiller 5.0.x JoboptionsDieser Report wurde automatisch mit Hilfe der Adobe Acrobat Distiller Erweiterung "Distiller Secrets v1.0.5" der IMPRESSED GmbH erstellt.Sie koennen diese Startup-Datei fr die Distiller Versionen 4.0.5 und 5.0.x kostenlos unter http://www.impressed.de herunterladen.

    ALLGEMEIN ----------------------------------------Dateioptionen: Kompatibilitt: PDF 1.3 Fr schnelle Web-Anzeige optimieren: Ja Piktogramme einbetten: Ja Seiten automatisch drehen: Nein Seiten von: 1 Seiten bis: Alle Seiten Bund: Links Auflsung: [ 2400 2400 ] dpi Papierformat: [ 481 680 ] Punkt

    KOMPRIMIERUNG ----------------------------------------Farbbilder: Downsampling: Nein Komprimieren: Ja Komprimierungsart: ZIP Bitanzahl pro Pixel: 8 BitGraustufenbilder: Downsampling: Nein Komprimieren: Ja Komprimierungsart: ZIP Bitanzahl pro Pixel: 8 BitSchwarzwei-Bilder: Downsampling: Nein Komprimieren: Ja Komprimierungsart: CCITT CCITT-Gruppe: 4 Graustufen gltten: Nein

    Text und Vektorgrafiken komprimieren: Ja

    SCHRIFTEN ---------------------------------------- Alle Schriften einbetten: Ja Untergruppen aller eingebetteten Schriften: Nein Wenn Einbetten fehlschlgt: Warnen und weiterEinbetten: Immer einbetten: [ /Courier-BoldOblique /Helvetica-BoldOblique /Courier /Helvetica-Bold /Times-Bold /Courier-Bold /Helvetica /Times-BoldItalic /Times-Roman /ZapfDingbats /Times-Italic /Helvetica-Oblique /Courier-Oblique /Symbol ] Nie einbetten: [ ]

    FARBE(N) ----------------------------------------Farbmanagement: Farbumrechnungsmethode: Farbe nicht ndern Methode: StandardGerteabhngige Daten: Einstellungen fr berdrucken beibehalten: Ja Unterfarbreduktion und Schwarzaufbau beibehalten: Ja Transferfunktionen: Beibehalten Rastereinstellungen beibehalten: Nein

    ERWEITERT ----------------------------------------Optionen: Prolog/Epilog verwenden: Nein PostScript-Datei darf Einstellungen berschreiben: Nein Level 2 copypage-Semantik beibehalten: Ja Portable Job Ticket in PDF-Datei speichern: Ja Illustrator-berdruckmodus: Ja Farbverlufe zu weichen Nuancen konvertieren: Ja ASCII-Format: NeinDocument Structuring Conventions (DSC): DSC-Kommentare verarbeiten: Ja DSC-Warnungen protokollieren: Nein Fr EPS-Dateien Seitengre ndern und Grafiken zentrieren: Ja EPS-Info von DSC beibehalten: Ja OPI-Kommentare beibehalten: Nein Dokumentinfo von DSC beibehalten: Ja

    ANDERE ---------------------------------------- Distiller-Kern Version: 5000 ZIP-Komprimierung verwenden: Ja Optimierungen deaktivieren: Nein Bildspeicher: 524288 Byte Farbbilder gltten: Nein Graustufenbilder gltten: Nein Bilder (< 257 Farben) in indizierten Farbraum konvertieren: Ja sRGB ICC-Profil: sRGB IEC61966-2.1

    ENDE DES REPORTS ----------------------------------------

    IMPRESSED GmbHBahrenfelder Chaussee 4922761 Hamburg, GermanyTel. +49 40 897189-0Fax +49 40 897189-71Email: info@impressed.deWeb: www.impressed.de

    Adobe Acrobat Distiller 5.0.x Joboption Datei

    /ColorImageDownsampleType /Bicubic /GrayImageDict > /CalCMYKProfile (U.S. Web Coated (SWOP) v2) /ParseDSCComments true /PreserveEPSInfo true /MonoImageDepth -1 /AutoFilterGrayImages false /SubsetFonts false /GrayACSImageDict > /ColorImageFilter /FlateEncode /AutoRotatePages /None /PreserveCopyPage true /EncodeMonoImages true /ASCII85EncodePages false /PreserveOPIComments false /NeverEmbed [ ] /ColorImageDict > /AntiAliasGrayImages false /GrayImageDepth 8 /CannotEmbedFontPolicy /Warning /EndPage -1 /TransferFunctionInfo /Preserve /CalRGBProfile (sRGB IEC61966-2.1) /EncodeColorImages true /EncodeGrayImages true /ColorACSImageDict > /Optimize true /ParseDSCCommentsForDocInfo true /GrayImageDownsampleThreshold 1.5 /MonoImageDownsampleThreshold 1.5 /AutoPositionEPSFiles true /GrayImageResolution 300 /AutoFilterColorImages false /AlwaysEmbed [ /Courier-BoldOblique /Helvetica-BoldOblique /Courier /Helvetica-Bold /Times-Bold /Courier-Bold /Helvetica /Times-BoldItalic /Times-Roman /ZapfDingbats /Times-Italic /Helvetica-Oblique /Courier-Oblique /Symbol ] /ImageMemory 524288 /OPM 1 /DefaultRenderingIntent /Default /EmbedAllFonts true /StartPage 1 /DownsampleGrayImages false /AntiAliasColorImages false /ConvertImagesToIndexed true /PreserveHalftoneInfo false /CompressPages true /Binding /Left>> setdistillerparams> setpagedevice

  • and temperature profiles. General criteria for selection of these two properties forrobust immobilized enzymes as catalysts are proposed in Table 1.1 [16].

    In practice, catalytic functions are designed in line with the desired activity, se-lectivity, substrate specificity, productivity and spacetime yield, with the aim ofachieving fewer side reactions, high tolerance of structural variation of the sub-strates, high productivity, high spacetime yield, and high durability of the catalyst.On the other hand, the selection criteria for non-catalytic functions, especially geo-metric properties, are largely dependent on the design of reactor configurations(e.g. batch, stir-tank, column and plug-flow), the types of reaction medium (aque-ous, organic solvent, or two-phase system), the reaction systems (slurry, liquid-to-liquid, liquid-to-solid, or solid-to-solid), and the process conditions (pH, tempera-ture, pressure). The objectives when designing the non-catalytic properties aremainly to achieve easy separation of the immobilized enzymes from the reactionmixtures, broad reactor considerations (i.e. flexibility of reactor design), broad ap-plicability in different reaction media and reaction systems, and facilitating pro-cess development, down-stream processing and, particularly, control of the pro-cess.

    It is usually the peculiarities of these two essential elements, i.e. the non-catalyt-ic functions and the catalytic functions that dictate the scope of the final applicationof the immobilized enzymes obtained. Conversely, the peculiarities of each appli-cation also dictate the design and selection of the two essential elements. In gener-al, the NCF and CF of an immobilized enzyme are the two sides of a coin which arethe basis of the scope of the final application, as illustrated in Scheme 1.2.

    It is, therefore, hardly surprising that the main task of enzyme immobilization isto select a suitable immobilization method (carriers, conditions, and enzymes) todesign an immobilized biocatalyst which can meet not only the catalytic needs (ex-pressed as productivity, spacetime yield, stability and selectivity) but also the non-catalytic needs (e.g. separation, control, down-streaming process) of a given appli-

    2 1 Introduction: Immobilized Enzymes: Past, Present and Prospects

    z

    Chemical stability

    Scheme 1.2 Relationship between NCF and CF of an immobilized enzyme and its applications.

    Verwendete Mac Distiller 5.0.x JoboptionsDieser Report wurde automatisch mit Hilfe der Adobe Acrobat Distiller Erweiterung "Distiller Secrets v1.0.5" der IMPRESSED GmbH erstellt.Sie koennen diese Startup-Datei fr die Distiller Versionen 4.0.5 und 5.0.x kostenlos unter http://www.impressed.de herunterladen.

    ALLGEMEIN ----------------------------------------Dateioptionen: Kompatibilitt: PDF 1.3 Fr schnelle Web-Anzeige optimieren: Ja Piktogramme einbetten: Ja Seiten automatisch drehen: Nein Seiten von: 1 Seiten bis: Alle Seiten Bund: Links Auflsung: [ 2400 2400 ] dpi Papierformat: [ 481 680 ] Punkt

    KOMPRIMIERUNG ----------------------------------------Farbbilder: Downsampling: Nein Komprimieren: Ja Komprimierungsart: ZIP Bitanzahl pro Pixel: 8 BitGraustufenbilder: D

Recommended

View more >