Biocatalysis, DESs

In this volume not all stress types are treated. Various aspects have been reviewed recently by various authors e.g. The effects of oxygen on recombinant protein expression by Konz et al. [2]. The Mechanisms by which bacterial cells respond to pH was considered in a Symposium in 1999 [3] and solvent effects were reviewed by de Bont in the article Solvent-tolerant bacteria in biocatalysis [4]. Therefore, these aspects are not considered in this volume. Influence of fluid dynamical stresses on micro-organism, animal and plant cells are in center of interest in this volume. In chapter 2, H.-J. Henzler discusses the quantitative evaluation of fluid dynamical stresses in various type of reactors with different methods based on investigations performed on laboratory an pilot plant scales. S. S. Yim and A. Shamlou give a general review on the effects of fluid dynamical and mechanical stresses on micro-organisms and bio-polymers in chapter 3. G. Ketzmer describes the effects of shear stress on adherent cells in chapter 4. Finally, in chapter 5, P. Kieran considers the influence of stress on plant cells. 

Ulijn, R,V., De Martin, L., Gardossi L. and Hailing, P.J., Biocatalysis in reaction mixtures with undissolved solid substrates and products. Curr. Org. Chem., 2003, 7, 1333-1346. 

In vitro multi-enzyme systems are set up by the combination of enzyme modules including pathway and even pathway-unrelated enzymes. Also, the synthesis of saccharides in combination with de novo enzymatic sugar synthesis can be accomplished. This so-called combinatorial biocatalysis can be performed in sequential reactors or in a one-pot reaction vessel which challenges further reaction engineering for optimization. Even the combination of an enzyme module with a chemical... 

Ulijn RV, De Martin L, Gardossi L, Hailing PJ (2003) Biocatalysis with mainly undissolved solid substrates. Curr Org Chem 7 1333-1346... 

In this reactor the product could be synthesized with a space-time yield of 64 g d with an excellent enantiomeric and diastereomeric excess ee and de >99%). The biocatalyst consumption could be decreased 30-fold to 15 gproduct gwcw by using the membrane reactor as compared with a batch reactor. The corresponding (2S,5S)-hexanediol can also be obtained via biocatalysis [20]. 

Fig. 23.1 Microbial routes from natural raw materials to and between natural flavour compounds (solid arrows). Natural raw materials are depicted within the ellipse. Raw material fractions are derived from their natural sources by conventional means, such as extraction and hydrolysis (dotted arrows). De novo indicates flavour compounds which arise from microbial cultures by de novo biosynthesis (e.g. on glucose or other carbon sources) and not by biotransformation of an externally added precursor. It should be noted that there are many more flavour compounds accessible by biocatalysis using free enzymes which are not described in this chapter, especially flavour esters by esterification of natural alcohols (e.g. aliphatic or terpene alcohols) with natural acids by free lipases. For the sake of completeness, the C6 aldehydes are also shown although only the formation of the corresponding alcohols involves microbial cells as catalysts. The list of flavour compounds shown is not intended to be all-embracing but focuses on the examples discussed in this chapter... 

An excellent example of the successful combination of chemo- and biocatalysis in a two-step cascade process is provided by the dynamic kinetic resolutions (DKR) of chiral alcohols and amines. We first suggested [6], in 1993, that (de)-hydrogenation catalysts should be capable of catalyzing the racemization of chiral alcohols and amines via a dehydrogenation/hydrogenation mechanism as shown in Fig. 9.1. 

Panella L, Broos J, Jin JF, Fraaije MW, Janssen DB, Jeronimus-Stratingh M, Feringa BL, Minnaard AJ, de Vries JG. Merging homogeneous catalysis with biocatalysis papain as hydrogenation catalyst. Chem. Commun. 2005 45 5656-5658. 

Krieger N, Bhatnagar T, Baratti JC, Baron AM, De Lima VM, and Mitchell D. Non-aqueous biocatalysis in heterogeneous solvent systems. Food Technol. Biotechnol. 2004 42(4) 279-286. 

Robertson DE, Bomscheuer UT. Biocatalysis and biotransformation new technologies, enzymes and challenges. Current Opinion in Chemical Biology 9(2), 164, 2005. 

Patel RN. Tour de paclitaxel biocatalysis for semisynthesis. Annual Review of Microbiology 98, 361,1995. 

Biocatalysis in supercritical fluids, fluorous solvents, and under solvent-free conditions was recently reviewed (80). In this book, de Geus et al (17), Villarroya (41) and Bruns et al (32) all provide important examples of how supercritical CO2 can be used for enzyme-catalyzed reactions. Furthermore, Srienc et al (38) used ionic liquid media for enzyme-catalyzed polymerizations of p-butyrolactone in order to prepare poly(hydroxyalkanoic acids), PHA. The role of ionic liquids was to both maintain enzyme activity and propagating chain solubility so that high molecular weight products could be obtained in monophasic media. 

Zhang Y, Furyk S, Bergbreiter DE, Cremer PS (2005) Specific ion effects on the water solubility of macromolecules PNIPAM and the Hofmeister series. J Am Chem Soc 127 14505-14510 Zhao HJ (2005) Effects of ions and other compatible solutes on enzymatic activity, and its implication for biocatalysis using ionic liquids. Mol Catal B Enzym 37 16-25... 

Bruggink A (2000), Green solutions for chemical challenges biocatalysis in the synthesis of semi-synthetic antibiotics. In Zwanenburg B, Mikolajczyk M, Kielbasinsky P (eds) Enzymes in action. NATO sciences series 1/33, Kluwer Academic, pp 449-458 Bruggink A, Roos EC, de Vroom E (1998) Penicillin acylase in the industrial production of lactam antibiotics.Org Process Res Dev2 128-133... 

Ortiz de Montellano PR (2010) Peroxidase catalytic mechanisms. In Torres E, Ayala M (eds) Biocatalysis based on heme peroxidases. Springer, New York, pp 79-110... 

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