Biocatalysis recent advances

If biocatalysis is so attractive, why was it not widely used in the past The answer is that only recent advances in biotechnology have made it possible. First, the availability of numerous whole-genome sequences has dramatically increased the number of potentially available enzymes. Second, in vitro evolution has enabled the manipulation of enzymes such that they exhibit the desired properties substrate specificity, activity, stability, and pH profile [42]. Third, recombinant DNA techniques have made it, in principle, possible to produce virtually any enzyme for a commercially acceptable price. Fourth, the cost-effective techniques that have now been developed for the immobilization of enzymes afford improved operational stability and enable their facile recovery and recycling [43]. 

Antibody Catalysis. Recent advances in biocatalysis have led to the generation of catalytic antibodies exhibiting aldolase activity by Lemer and Barbas. The antibody-catalyzed aldol addition reactions display remarkable enantioselectivity and substrate scope [18]. The requisite antibodies were produced through the process of reactive immunization wherein antibodies were raised against a [Tdiketone hapten. During the selection process, the presence of a suitably oriented lysine leads to the condensation of the -amine with the hapten. The formation of enaminone at the active site results in a molecular imprint that leads to the production of antibodies that function as aldol catalysts via a lysine-dependent class I aldolase mechanism (Eq. 8B2.12). 

Rubin-Pitel SB, Zhao H. Recent advances in biocatalysis by directed enzyme evolution. Comb. Chem. High Throughput Screen 2006 9 247-257. 

Due to increasing environmental problems, the use of metal catalysts will gradually be reduced in the future the reduction in the early use of lead- and chromium-based catalysts is evidence of this. With stricter regulations governing the release of metals, the cost of catalyst recovery and environmental remediation is quickly making noncatalytic processes for the production of carboxylic acids preferable. Coupled with recent advances in the field of biocatalysis, metal-mediated oxidations may give way to alternative processes as we enter a new millennium of chemistry. 

Whole-cell based biocatalysis utilizes an entire microorganism for the production of the desired product. One of the oldest examples for industrial applications of whole-cell biocatalysis is the production of acetic acid from ethanol with an immobilized Acetobacter strain, which was developed nearly 200 yr ago. The key advantage of whole-cell biocatalysis is the ability to use cheap and abundant raw materials and catalyze multistep reactions. Recent advances in metabolic engineering have brought a renaissance to whole-cell biocatalysis. In the following sections, two novel industrial processes that utilize whole-cell biocatalysis are discussed with emphasis on the important role played by metabolic engineering. 

In this chapter, we describe the recent trends in the field of electrochemical biodevices exploring the principal strategies utilized in the last years to improve signal response of enzymatic biocatalysis and describe briefly the electrochemical characteristics of several nanomaterials when utilized in modified electrodes. The fabrication of nanoelectrodes by some techniques is also explored in this chapter. In addition, we will discuss the many efforts in order to detect specific molecules in vitro and in vivo and recent advances in the development of implantable biosensors. 

Recent advances in biotechnology, also described as the "third wave of biocatalysis" by Bomscheuer et al. [6], have made available numerous whole-genome sequences leading to a dramatic increase in the number of potentially available enzymes. 

Consequently, many successful stories and a number of reviews have been reported recently in developing biocatalysis for the pharmaceutical industry, across drug discovery, development, and manufacturing. The book is dedicated to these advances, and divided into four parts ... 

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