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Candida antarctica

The report from Sheldon and co-workers was the second publication demonstrating the potential use of enzymes in ionic liquids and the first one for lipases (Entry 13) [43]. They compared the reactivity of Candida antarctica lipase in ionic liquids such as [BMIM][PFg] and [BMIM][BF4] with that in conventional organic solvents. In all cases the reaction rates were similar for all of the reactions investigated alcoholysis, ammoniolysis, and per hydrolysis. [Pg.344]

In principle, numerous reports have detailed the possibility to modify an enzyme to carry out a different type of reaction than that of its attributed function, and the possibility to modify the cofactor of the enzyme has been well explored [8,10]. Recently, the possibility to directly observe reactions, normally not catalyzed by an enzyme when choosing a modified substrate, has been reported under the concept of catalytic promiscuity [9], a phenomenon that is believed to be involved in the appearance of new enzyme functions during the course of evolution [23]. A recent example of catalytic promiscuity of possible interest for novel biotransformations concerns the discovery that mutation of the nucleophilic serine residue in the active site of Candida antarctica lipase B produces a mutant (SerlOSAla) capable of efficiently catalyzing the Michael addition of acetyl acetone to methyl vinyl ketone [24]. The oxyanion hole is believed to be complex and activate the carbonyl group of the electrophile, while the histidine nucleophile takes care of generating the acetyl acetonate anion by deprotonation of the carbon (Figure 3.5). [Pg.69]

Aqueous solutions are not suitable solvents for esterifications and transesterifications, and these reactions are carried out in organic solvents of low polarity [9-12]. However, enzymes are surrounded by a hydration shell or bound water that is required for the retention of structure and catalytic activity [13]. Polar hydrophilic solvents such as DMF, DMSO, acetone, and alcohols (log P<0, where P is the partition coefficient between octanol and water) are incompatible and lead to rapid denaturation. Common solvents for esterifications and transesterifications include alkanes (hexane/log P=3.5), aromatics (toluene/2.5, benzene/2), haloalkanes (CHCI3/2, CH2CI2/I.4), and ethers (diisopropyl ether/1.9, terf-butylmethyl ether/ 0.94, diethyl ether/0.85). Exceptionally stable enzymes such as Candida antarctica lipase B (CAL-B) have been used in more polar solvents (tetrahydrofuran/0.49, acetonitrile/—0.33). Room-temperature ionic liquids [14—17] and supercritical fluids [18] are also good media for a wide range of biotransformations. [Pg.134]

In recent years, a great variety of primary chiral amines have been obtained in enantiomerically pure form through this methodology. A representative example is the KR of some 2-phenylcycloalkanamines that has been performed by means of aminolysis reactions catalyzed by lipases (Scheme 7.17) [34]. Kazlauskas rule has been followed in all cases. The size of the cycle and the stereochemistry of the chiral centers of the amines had a strong influence on both the enantiomeric ratio and the reaction rate of these aminolysis processes. CALB showed excellent enantioselec-tivities toward frans-2-phenylcyclohexanamine in a variety of reaction conditions ( >150), but the reaction was markedly slower and occurred with very poor enantioselectivity with the cis-isomer, whereas Candida antarctica lipase A (GALA) was the best catalyst for the acylation of cis-2-phenylcyclohexanamine ( = 34) and frans-2-phenylcyclopropanamine ( =7). Resolution of both cis- and frans-2-phenyl-cyclopentanamine was efficiently catalyzed by CALB obtaining all stereoisomers with high enantiomeric excess. [Pg.181]

For desymmetrization of diesters 3 via their hydrolysis in water, pig Hver esterase [12], o -chymotrypsin [12, 13a], and Candida antarctica Hpase (CAL-B) [14] were successfully used. However, further studies showed that respective anhydrides 5 can be used as substrates for enzyme-catalyzed desymmetrization in organic solvents [15]. The desired monoesters 4 were obtained in high yield in this way, using immobilized enzymes Novozym 435 or Chirazyme L-2 (Scheme 5.3). After the reaction, enzymes were filtered off, organic solvents were evaporated, and the crude products were crystalHzed. This was a much simpler experimental procedure in which control of the reaction progress was not necessary, and aU problems associated with extraction of products from aqueous phase and their further purification were omitted [15]. [Pg.99]

We initially tested Candida antarctica lipase using imidazolium salt as solvent because CAL was found to be the best enzyme to resolve our model substrate 5-phenyl-l-penten-3-ol (la) the acylation rate was strongly dependent on the anionic part of the solvents. The best results were recorded when [bmim][BF4] was employed as the solvent, and the reaction rate was nearly equal to that of the reference reaction in diisopropyl ether. The second choice of solvent was [bmim][PFg]. On the contrary, a significant drop in the reaction rate was obtained when the reaction was carried out in TFA salt or OTf salt. From these results, we concluded that BF4 salt and PFg salt were suitable solvents for the present lipase-catalyzed reaction. Acylation of la was accomplished by these four enzymes Candida antarctica lipase, lipase QL from Alcaligenes, Lipase PS from Burkholderia cepacia and Candida rugosa lipase. In contrast, no reaction took place when PPL or PLE was used as catalyst in this solvent system. These results were established in March 2000 but we encountered a serious problem in that the results were significantly dependent on the lot of the ILs that we prepared ourselves. The problem was very serious because sometimes the reaction did not proceed at all. So we attempted to purify the ILs and established a very successful procedure (Fig. 3) the salt was first washed with a mixed solvent of hexane and ethyl acetate (2 1 or 4 1), treated with activated charcoal and passed into activated alumina neutral type I as an acetone solution. It was evaporated and dried under reduced... [Pg.5]

Enzymes PPL, lipase from Pseudomonas fluorescens F-AP, lipase from Rhizopus orizae AP-6, lipase from Aspergillus niger, SP-254, lipase from Aspergillus oryzae P-2, Chirazyme WCPC, whole cell cultures of Penicillium citrinum WCPFL, whole cell cultures of Pseudomona fluorescens CAL-B, lipase from Candida antarctica B PS-C, lipase from Pseudomonas cepacia GCL, lipase from Geotrichum candidum. n.r. not reported. [Pg.175]

Lipase ANL, lipase from Aspergillus niger, BCL, lipase from Burkholderia cepacia (formerly Pseudomonas cepacia) CAL-B, lipase from Candida antarctica B PPL, lipase from Pseudomonas fluorescens PPL, pig pancreatic lipase. [Pg.192]

In polyester synthesis via ring-opening polymerizations, metal catalysts are often used. For medical applications of polyesters, however, there has been concern about harmful effects of the metallic residues. Enzymatic synthesis of a metal-free polyester was demonstrated by the polymerization of l,4-dioxan-2-one using Candida antarctica lipase (lipase CA). Under appropriate reaction conditions, the high molecular weight polymer (molecular weight = 4.1 x 10" ) was obtained. [Pg.208]

The use of an enzyme in a cascade using nanoencapsulation has also been demonstrated [23]. In this case, the dynamic kinetic resolution (DKR) of secondary alcohols was achieved with an acidic zeolite and an incompatible enzyme, Candida antarctica lipase B (CALB) (Scheme 5.8). [Pg.141]

A combination of an enzymatic kinetic resolution and an intramolecular Diels-Alder has recently been described by Kita and coworkers [23]. In the first step of this domino process, the racemic alcohols ( )-8-55 are esterified in the presence of a Candida antarctica lipase (CALB) by using the functionalized alkenyl ester 8-56 to give (R)-8-57, which in the subsequent Diels-Alder reaction led to 8-58 in high enantioselectivity of 95 and 91 % ee, respectively and 81 % yield (Scheme 8.15). In-... [Pg.538]

An example of the appropriate application of organically-modified silica precursors is alkoxides with an alkyl group. When methyltrimethoxy- or methyl-triethoxysilane (Figure 3.2) was added in formulations to increase the hydro-phobicity of ORMOSILs, it resulted in a better enzymatic activity of lipases immobilized in the alkyl-modified silica than in a hydrophilic matrix fabricated by means ofTEOS alone [51,80,129-133]. Similarly, an increased stability of lipase from Candida antarctica B was observed after its immobilization in a silica matrix... [Pg.86]

The concept of zeolite action was tested in a particular reaction where the enzyme is exposed from the beginning to an acidic environment the esterification of geraniol with acetic acid catalyzed by Candida antarctica lipase B immobilized on zeolite NaA [219]. Lipases have been used for the hydrolysis of triglycerides and due to their ambivalent hydrophobic/hydrophilic properties they are effective biocatalysts for the hydrolysis of hydrophobic substrates [220]. When water-soluble lipases are used in organic media they have to be immobilized on solid supports in order to exhibit significant catalytic activity. [Pg.469]

In conventional synthetic transformations, enzymes are normally used in aqueous or organic solvent at moderate temperatures to preserve the activity of enzymes. Consequently, some of these reactions require longer reaction times. In view of the newer developments wherein enzymes can be immobilized on solid supports [183], they are amenable to relatively higher temperature reaction with adequate pH control. The application of MW irradiation has been explored with two enzyme systems namely Pseudomonas lipase dispersed in Hyflo Super Cell and commercially available SP 435 Novozym (Candida antarctica lipase grafted on an acrylic resin). [Pg.211]

Systems such as Pseudomonas lipase dispersed inside Hyflo Supercell (a diatoma-ceous silica of pH 8.5-9) and SP 435 Novozym (Candida antarctica lipase grafted on an acrylic resin) are thermally stable and have optimum activity in the range 80-100 °C. They can therefore be used with conventional or microwave heating if the temperature is strictly controlled. [Pg.279]

The multipolymer enzymatic resolution of soluble polymer-supported alcohols 42 and 43 was achieved using an immobilised lipase from Candida Antarctica (Novozym 435). The R-alcohol was obtained in enantiomerically pure form (>99% ee) after its cleavage from the poly(ethylene) glycol (PEG) scaffold . The achiral hydantoin- and isoxazoline-substituted dispirocyclobutanoids 47 were produced using both solution and solid-phase synthesis <00JOC3520, OOCC1835>. [Pg.220]

Pseudomonas putida esterase or pig liver esterase, (pie) or proteases (e.g. sub-tilisin) are employed in the reactions described in equation (1), while lipases (e.g. Candida antarctica lipase) are more often used for transformations illustrated in... [Pg.7]

Candesartan, molecular formula and structure, 5 152t Candida, 26 446 Candida albicans, 26 475 Candida antarctica lipase B, 70 307 Candida glabrata, genome of, 26 450t Candida utilis, 26 473 Candle filters, 77 362—363 Cando-luminescence, cerium application in, 5 689... [Pg.136]

Biocatalysts also operate in ionic liquids [28]. The ones that have been most widely investigated are the lipase family of enzymes. For example, Candida Antarctica lipase B immobilized in [bmim][BF4] or [bmim][PFe] under anhydrous conditions is able to catalyse transesterifications at rates comparable to those observed in other solvents. Certain lipase mediated enantioselective acylations have even resulted in considerable improvements in enantiomeric excesses... [Pg.91]

Candida antarctica lipase in hexane catalyses the conversion of primary amines RNH2 (R = Bu, CgHi7, C10H21, Ci2H25 and PhCH2) into the (R)-amines 294 by ethyl (S)-2-methylbutanoate336. [Pg.592]


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Antarctica

Candida

Candida antarctica cylindracea

Candida antarctica humicola

Candida antarctica immobilized lipase from

Candida antarctica lipase

Candida antarctica lipase A

Candida antarctica lipase B

Candida antarctica lipase B (CAL

Candida antarctica lipase B (CALB

Candida antarctica lipase B immobilization

Candida antarctica lipase CALA)

Candida antarctica lipase CALB)

Candida antarctica lipase alcohols

Candida antarctica lipase dynamic kinetic resolution

Candida antarctica lipase regioselective acylation

Candida antarctica lipase substrates

Candida antarctica lipase vinyl carbonates

Candida antarctica lipase, enzymatic reactions

Candida antarctica rugosa

Candida antarctica, lipase synthesis

Enzymatic synthesis Candida antarctica

Enzyme novozym [ Candida antarctica)

Improved Immobilization Supports for Candida Antarctica Lipase

Lipase B from Candida antarctica

Lipases Candida antarctica lipase

Mechanism Candida antarctica lipase

Novozym Candida antarctica lipase

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