Biocatalysis in Supercritical Fluids, in Fluorous Solvents, and under Solvent-Free Conditions

Hobbs, Helen R.; Thomas, Neil R.

doi:10.1021/cr0683820

Cited by 250 publications

(107 citation statements)

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“…72,78,[81][82][83][84] The chief advantage of SCFs is the tunability of the properties of the solvent, through slight changes of the pressure and/or temperature. It is well established that success of biocatalysis (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…99 Reductions in reaction rate were found with increasing hydrophobicity of solvents. 82 The principal drawback to the use of SCFs is the requirement of specialised equipment that can withstand high pressures which has an associated increase in cost on plant scale. Adverse effects on enzymes have also been documented, scCO 2 has been reported to form carbamates (Scheme 5) between CO 2 and the amine groups on lysine residues, or potentially the imidazole side chain of histidine on the enzyme surface, which can lead to enzyme deactivation.…”

Section: Methodsmentioning

confidence: 99%

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Recent trends in whole cell and isolated enzymes in enantioselective synthesis

Milner¹,

Maguire²

2012

Arkivoc

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Modern synthetic organic chemistry has experienced an enormous growth in biocatalytic methodologies; enzymatic transformations and whole cell bioconversions have become generally accepted synthetic tools for asymmetric synthesis. This review details an overview of the latest achievements in biocatalytic methodologies for the synthesis of enantiopure compounds with a particular focus on chemoenzymatic synthesis in non-aqueous media, immobilisation technology and dynamic kinetic resolution. Furthermore, recent advances in ketoreductase technology and their applications are also presented.Keywords: Biocatalysis, kinetic and dynamic kinetic resolution, Baker's yeast, ketoreductases General IntroductionAsymmetric synthesis is the preferential formation of one stereoisomer of a chiral target compound to another; when scientists at GlaxoSmithKline, AstraZeneca and Pfizer 1 examined 128 syntheses from their companies, they found as many as half of the drug compounds made by their process research and development groups are not only chiral but also contain an average of two chiral centres each. 2In 2006 just 25 % were derived from the chiral pool and over 50 % employed chiral technologies. 1In order to meet regulatory requirements enantiomeric purities of 99.5 % were deemed necessary by the FDA. 3 This is one of the biggest challenges which face chemists today, primarily due to the recognition of the fact that different enantiomers of the same compound can interact differently in biological systems. As a consequence, the production of single enantiomers instead of racemic mixtures has become an important process in the pharmaceutical and agrochemical industry. Several routes can lead to the desired enantiomer including transition metal-, [4][5][6] organo-5,7-10 and bio-catalysis [11][12][13][14][15] and these have been thoroughly reviewed in the literature. 16,17 2. Biocatalysis IntroductionBiocatalysis involves the use of enzymes or whole cells (containing the desired enzyme or enzyme system) as catalysts for chemical reactions. A timeline of historic events in biocatalysis and biotechnology is outlined in Table 1. [18][19][20] Reviews and Accounts Novel methodologies for discovering industrial enzymes based on genomic sequencing and phage display (discussed further in Section 1.3), 21,22 as well as highly effective optimisation tools based on chemical, physical and molecular biology approaches, 23 have improved the access to biocatalysts, increased their stability, and radically broadened their specificity. 24This greater availability of catalysts with superior qualities including the use of new bioengineering tools contributed significantly to the development of new industrial processes. Biocatalytic methodologies for organic synthesis were outlined by Woodley et al. in three categories: established, emerging and expanding chemistries as depicted in Figure 1. 25 Enzyme classesBy the late 1950s it had become evident that the nomenclature of enzymes without any guiding authority, in a period when the...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Recent trends in whole cell and isolated enzymes in enantioselective synthesis

Milner¹,

Maguire²

2012

Arkivoc

View full text Add to dashboard Cite

show abstract

“…[141][142][143][144][145][146][147][148] The effect of compression and decompression of CO 2 may also affect the long-term stability of the enzyme, Kasche et al found that a-chymotrypsin and trypsin were partially denatured by the decompression step of scCO 2 . [149] Immobilized enzymes have been shown to be more resistant to changes in the physical state of the scCO 2 ; the degree of increased stability depending on which physical or chemical immobilization method is used and on the structure of the enzyme itself.…”

Section: Biocatalysismentioning

confidence: 99%

Generation, Capture, and Utilization of Industrial Carbon Dioxide

et al. 2010

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As a carbon-based life form living in a predominantly carbon-based environment, it is not surprising that we have created a carbon-based consumer society. Our principle sources of energy are carbon-based (coal, oil, and gas) and many of our consumer goods are derived from organic (i.e., carbon-based) chemicals (including plastics, fabrics and materials, personal care and cleaning products, dyes, and coatings). Even our large-volume inorganic-chemicals-based industries, including fertilizers and construction materials, rely on the consumption of carbon, notably in the form of large amounts of energy. The environmental problems which we now face and of which we are becoming increasingly aware result from a human-induced disturbance in the natural carbon cycle of the Earth caused by transferring large quantities of terrestrial carbon (coal, oil, and gas) to the atmosphere, mostly in the form of carbon dioxide. Carbon is by no means the only element whose natural cycle we have disturbed: we are transferring significant quantities of elements including phosphorus, sulfur, copper, and platinum from natural sinks or ores built up over millions of years to unnatural fates in the form of what we refer to as waste or pollution. However, our complete dependence on the carbon cycle means that its disturbance deserves special attention, as is now manifest in indicators such as climate change and escalating public concern over global warming. As with all disturbances in materials balances, we can seek to alleviate the problem by (1) dematerialization: a reduction in consumption; (2) rematerialization: a change in what we consume; or (3) transmaterialization: changing our attitude towards resources and waste. The "low-carbon" mantra that is popularly cited by organizations ranging from nongovernmental organizations to multinational companies and from local authorities to national governments is based on a combination of (1) and (2) (reducing carbon consumption though greater efficiency and lower per capita consumption, and replacing fossil energy sources with sources such as wind, wave, and solar, respectively). "Low carbon" is of inherently less value to the chemical and plastics industries at least in terms of raw materials although a version of (2), the use of biomass, does apply, especially if we use carbon sources that are renewable on a human timescale. There is however, another renewable, natural source of carbon that is widely available and for which greater utilization would help restore material balance and the natural cycle for carbon in terms of resource and waste. CO(2), perhaps the most widely discussed and feared chemical in modern society, is as fundamental to our survival as water, and like water we need to better understand the human as well as natural production and consumption of CO(2) so that we can attempt to get these into a sustainable balance. Current utilization of this valuable resource by the chemical industry is only 90 megatonne per year, compared to the 26.3 gigatonne CO(2) generated annually by c...

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“…The reaction involving the substrate and catalyst can occur at the higher temperature, and then facile separation of the two components is facilitated by simply lowering the temperature following reaction. While the application of such a system to biocatalytic polymerization has not yet been realized, biocatalysis itself has been reported and a nice review has recently been published [94] . This concept defi nitely has potential as a future ' exotic ' solvent for biocatalytic polymerization.…”

Section: Fluorous Biphasic Polymerizationmentioning

confidence: 99%