Candida moieties

The formation of optically active acyloins is also catalyzed by the yeast Candida Pareri if the bacteria Zymomonas mobilis and Zymomonas carlbergensis42 and the fungus Diplodia gossypina43. The latter microorganism produces (3/ ,66 )-6-hydroxy-7-oxo-8-norcitronellene from (/ )-citronellene by a reaction sequence that converts (7d)-citronellene to (/ )-4-methyl-5-butenal followed by addition of the acetyl moiety to the / e-face of the aldehyde. 

Layered phosphate/phosphonate and phosphonate materials, obtained by substitution of the phosphate moiety by phosphonate groups, display interesting tunable hydrophilic/organophilic properties for adsorption processes. When Candida rugosa lipase (CRL) is simply equilibrated with zirconium phosphate and phosphonate [135,136], immobilization was demonstrated to take place at the surface of the microcrystals. However, because lipase exhibits a strong hydrophobic character, its uptake by zirconium phosphate and phosphonate was much more related to the hydrophobic/hydrophilic character of the supports than to the surface area properties. A higher uptake is observed for zirconium-phenylphosphonate (78 %)... 

This process has many benefits in the context of green chemistry it involves two enzymatic steps, in a one-pot procedure, in water as solvent at ambient temperature. It has one shortcoming, however-penicillin acylase generally works well only with amines containing an aromatic moiety and poor enantioselectivities are often observed with simple aliphatic amines. Hence, for the easy-on/easy-off resolution of aliphatic amines a hybrid form was developed in which a hpase [Candida antarctica hpase B (CALB)] was used for the acylation step and peniciUin acylase for the deacylahon step [22]. The structure of the acyl donor was also optimized to combine a high enanhoselectivity in the first step with facile deacylation in the second step. It was found that pyridyl-3-acetic acid esters gave optimum results (see Scheme 6.8). 

The rather complex furylvinylcarbinol derivative 76 shown in Scheme 4.28 was required in enantiopure form as a key intermediate in the synthesis of the natural product cneorin. The carbinol moiety is heavily substituted with sterically demanding groups. Therefore attempts to resolve the furylvinylcarbinol with CALB or lipase PS-II led to very slow reactions. However, the rarely used enzyme Candida antarctica lipase A (CALA), which is known to act on sterically hindered substrates offers an alternative. Thus acylation of the furylvinylcarbinol 76 with 2,2,2-trifluoroethyl butanoate catalyzed by CALA (immobilized on celite with sucrose at pH 7.9) furnished the enantiomerically enriched propanoate of S-76 and R-76 (Scheme 4.28) [90]. Small-scale experiments gave E > 300. 

Other authors have described the lipase-catalyzed chemoselective acylation of alcohols in the presence of phenolic moities [14], the protease-catalyzed acylation of the 17-amino moiety of an estradiol derivative [15], the chemoselectivity in the aminolysis reaction of methyl acrylate (amide formation vs the favored Michael addition) catalyzed by Candida antarctica lipase (Novozym 435) [16], and the lipase preference for the O-esterification in the presence of thiol moieties, as, for instance, in 2-mercaptoethanol and dithiotreitol [17]. This last finding was recently exploited for the synthesis of thiol end-functionalized polyesters by enzymatic polymerization of e-caprolactone initiated by 2-mercaptoethanol (Figure 6.2)... 

FQ possesses planar chirality due to its 1,2-unsymmetrically substituted ferrocene moiety (Fig. 21). In the laboratory, a synthetic method was developed to provide separate pure enantiomers of FQ [126], The approach included a biocata-lytic kinetic resolution using Candida rugosa lipase (C.r.l.). The key step (Fig. 22)... 

Sophorolipids (SLs) are extracellular glycolipids that are normally synthesized from glucose and a fatty acid source (either FFA or triacylglycerol) by a number of yeasts (primarily Candida bombicola). They are composed of a disaccharide (sophorose 2-O-P-D-glucopyranosyl-p-D glucopyranose) attached to a hydroxy fatty acyl moiety at the co-1 or co carbon (Fig. 7.5). Typi-... 

Derivatives of Sordarin antifungal agents 132 with 2 and 3 fused oxirane and thiirane moieties were synthesized for a structure-activity relationship (SAR) study <2002BML1371>. This compound possesses the opposite stereochemistry at the 2 and 3 positions of the pyranose portion and displayed a slight improvement in activity against Candida spp. 

Nakano, H., Kitahata, S., Tominaga, Y, and Takenishi, S. 1991. Esterification of glycosides with glycerol and trimethylolpropane moieties by Candida cylindracea lipase. Agric. Biol. Chem. 55 2083-2089. 

In 1965, an important modification of the chemical structure of bakers yeast mannan was made by Ballou and his co-workers. They pointed out that the longest branching moieties of this mannan correspond to a tetraose, 0-orD-mannopyranosyl (1 - 3) 0-(x-D-mannopyranosyl (1- 2) O-oc-o-mannopyranosyl (l->2) mannose (23). In 1967, the Canadian workers and Hasenclever published the modified findings of structural analysis of the mannan of several Candida strains including those of C. albicans serotype A, C. albicans serotype B, C. tropicalis, C. stellatoidea, and C. parapsilosis, affording evidence that all mannans contain small amounts of al->3 linked D-mannopyranosyl residues in addition to the large amounts of al->2 and ocl->6 linkages (24). ... 

The carbohydrate moiety of j3-D-fructofuranosidase of Candida utilis was suggested to be localized at certain sites of the enzyme protein. The oxidation of the sugar moeity with periodate to a certain extent had no effect on the enzyme activity, but the stability of the enzyme was decreased. This partially oxidized enzyme bound hide powder or nylon powder and the enzyme activity was retained. The enzyme was shown to be divided into glycoprotein sub-units of a similar molecular size when heated in the presence of sodium dodecyl sulphate. The enzyme did not dissociate upon treatment with reducing agent such as mercaptoethanol. 

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