Biocatalysis combined chemical/biocatalysi

The nitrile hydrates employed are selective and stop at the amide stage. However, they display no relevant enantioselectivity. The enantioselectivity in the processes is always introduced by an amidase (see for instance Schemes 6.27 and 6.28) in a second hydrolysis step. Overall the syntheses are, remarkably, often purely catalytic and combine chemical catalysis for reductions with biocatalysis for hydrolyses and the introduction of stereoinformation (Scheme 6.38). 

Special attention is given to the integration of biocatalysis with chemocatalysis, i.e., the combined use of enzymatic with homogeneous and/or heterogeneous catalysis in cascade conversions. The complementary strength of these forms of catalysis offers novel opportunities for multi-step conversions in concert for the production of speciality chemicals and food ingredients. In particular, multi-catalytic process options for the conversion of renewable feedstock into chemicals will be discussed on the basis of several carbohydrate cascade processes that are beneficial for the environment. 

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... 

Combination of Biocatalysis and Chemical Catalysis for the Preparation of Pharmaceuticals Through Multi-Step Syntheses... 

Nowadays, biocatalysis in combination with chemical catalysis has emerged in the pharmaceutical industry as a routine tool for the preparation of enantiopure drugs. 

Another challenge this book strives to address results from the interdisciplinary nature of the field of biocatalysis. Biocatalysis is a synthesis of chemistry, biology, chemical engineering, and bioengineering, but most students and practitioners enter this field with preparation essentially limited to one of the major contributing areas, or at best two. The essence of biocatalysis, as well as most of its current research, however, is captured in the interdisciplinary overlap between individual areas. Therefore, this work seeks to help readers to combine their prior knowledge with the contents and the methods in this book to make an integrated whole. 

Biocatalysis is a main part of white biotechnology and in combination with the usage of renewable primary products should lead to a more sustainable chemical and pharmaceutical industry. 

Combining whole-cell biocatalysis and radical polymerization, researchers at Imperial Chemical Industries (ICI) published a chemoenzymatic route to high-molecular-weight poly(phenylene) [86], This polymer is used in the fibers and coatings industry. However, since it is practically insoluble, the challenge was to make a soluble polymer precursor that could first be coated or spun, and only then converted to poly(phenylene). The ICI process starts from benzene, which is oxidized by Pseudomonas putida cells to cyclohexa-3,5-diene-l,2-diol (see Figure 5.17). The... 

An interesting alternative that combines the advantages of both classical and quantum mechanics is to use hybrid QM/MM models, first introduced by Arieh Warshel for modeling enzymatic reactions [7]. Here, the chemical species at the active site are treated using high-level (and therefore expensive) QM models, which are coupled to a force field that describes the reaction environment. Hybrid models can thus take into account solvent effects in homogeneous catalysis, support structure and interface effects in heterogeneous catalysis, and enzyme structure effects in biocatalysis. 

Since pharmaceuticals are becoming increasingly complex molecules, we will keep strengthening our science base in this area too, by combining our internal skills with relevant external expertise in fermentation, biocatalysis, biotransformation, and chemical synthesis. 

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