细胞技术

The oxidation of aromatic compounds is important in producing chemical intermediates for the chemical and pharmaceutical industries (1,2). Conventional aromatic oxidation reactions are prone to byproduct formation and often require heavy-metal catalysts, extremes of tem ...

The United States consumes approximately 16–17 million barrels of crude oil per day, and the majority is used for electricity, heating, and transportation fuel (1). The main constituents of crude oil are linear aliphatics. Clearly, the selective hydroxylation of alkanes to more valuable pr ...

Peroxidases catalyze the decomposition of hydrogen peroxide coupled to the oxidation of a variety of organic and inorganic substrates. Produced by a broad variety of natural sources, most peroxidases use heme or vanadium as a cofactor at the redox active site, while some bacterial peroxid ...

Screening conditions should simulate the final application as closely as possible. This is especially a challenge when chromophore-free (e.g., aliphatic) substrates are used and no simple and reliable high-throughput method for quantitative analysis of the respective reaction ...

Oxidases remove hydrogen from substrates, transferring it to molecular oxygen to generate hydrogen peroxide or water. Since oxidases catalyze fundamental synthetic transformations, including alcohol-aldehyde and aldehyde-carboxylic acid conversions, they have att ...

In this chapter, we describe colorimetric methods for screening laccases using natural and nonnatural substrates. Laccases (EC 1.10.3.1) are blue-copper enzymes that oxidize phenols, polyphenols, and anilines (1,2). The catalytic capabilities of laccase can be greatly enhanced by t ...

Dehydrogenases are studied for a variety of reasons. Several dehydrogenases are of use in industrial processes to produce pharmaceuticals and fine chemicals. Scientists are trying to enhance the performance of such enzymes by limiting substrate inhibition (1) and eliminating the n ...

Lipases and esterases are some of the most extensively used enzymes for biotransformations (1–3). This is in part due to their widely applicable chemistry, often exceptional regio- and stereo-selectivity, lack of required cofactors and their functionality in organic as well as aqueous m ...

Microbial hydrolytic haloalkane dehalogenases catalyze the cleavage of halogen-carbon bonds of a variety of aliphatic halogenated compounds, including a broad range of chlorinated (C2–C6) and brominated (C2–C8) alkanes, with water as the sole co-substrate, resulting in the prod ...

In principle there are two ways for the biocatalytic synthesis of α-hydroxyketones. Oxidoreductases may be used to convert diketones or diols into the respective α-hydroxyketones. This kind of reaction is exploited, e.g., in the industrial synthesis of the α-glucosidase inhibitor mig ...

Cellulases degrade cellulose, which is the most abundant biological polymer on the earth (1). Although the chemical composition of cellulose is very simple, consisting of only glucose residues connected by β-1,4-glycosidic bonds, no single enzyme is able to degrade crystalline cellul ...

Disulfide isomerases (EC 5.3.4.1) were first discovered almost 40 years ago by Christian Anfinsen, and have since been shown to occur in numerous organisms from bacteria to man (1). These enzymes play a key role in disulfide bond formation, an essential step in the oxidative folding of secreted prot ...

The directed evolution of enantioselective enzymes (1,2) for use in organic synthesis constitutes an attractive alternative to traditional forms of asymmetric catalysis based on chiral transition metal complexes or catalytic antibodies. It involves the proper combination of ...

A variety of in vivo selection and screening methods have been developed for the directed evolution of protein function. Typically, in vivo selection strategies involve the identification of new binding or catalytic functions based on their ability to confer a selective growth advanta ...

Directed evolution is a powerful technology for the isolation of enzyme variants with enhanced properties such as organic solvent tolerance (1), thermostability (2), glutaraldehyde resistance (3), and altered substrate specificity (4,5). Typically, enzyme variants are isolat ...

Directed evolution has proven to be a powerful route to enhance the stability, catalytic efficiency, or substrate specificity of enzymes. Large repertoires of enzyme mutants are generated, followed by the isolation of those enzyme variants with the desired catalytic properties. In th ...

Recombinant protein expression in heterologous hosts such as Escherichia coli (E. coli) can provide large amounts of a protein of interest. Often, expression can result in the accumulation of the recombinant protein as inactive, insoluble inclusion bodies (1). When attempts at refoldi ...

Directed evolution by sequential cycles of random mutagenesis and screening has proven to be useful for producing new or improved enzyme properties (1,2). The first step is construction of a mutant library, usually accomplished by random point mutagenesis with error-prone PCR (3) or by DNA sh ...

Functional gene expression is a prerequisite for directed evolution with Escherichia coli (E. coli), the preferred host organism. However, bacterial expression of eukaryotic genes can be impossible, or produce proteins with substantially altered properties, because of differ ...

The directed migration of cells (chemotaxis) occurs not only during wound healing and inflammatory responses but also during embryonic development. However, the intracellular signaling pathways that enable a cell to detect a chemoattractant and subsequently migrate toward the ...