Trigonopsis variabili

L-methionine DL-methionine + Asp D-amino acid oxidase + transaminase Trigonopsis variabilis ... 

Studies with resting free cells of Trigonopsis variabilis (DSM 70714) demonstrated that the enantiomeric purity of (R)-41 depends significantly on the substrate concentration... 

By analogy with the stereoselective microbial reduction of the acetylsilane rac-48 (Scheme 10) and its derivatives rac-51, rac-54 and rac-57, the related acetyldisilane rac- 60 was also found to be reduced (R)-selectively with resting free cells of Trigonopsis variabilis (DSM 70714) to give a 1 1 mixture of the corresponding diastereomeric... 

Chemical synthesis and isolation of 2-keto-6-hydroxyhexanoic acid required several steps. In a second, more convenient process (Fig. 2), the ketoacid was prepared by treatment of racemic 6-hydroxynorleucine [produced by hydrolysis of 5-(4-hydroxybutyl)hydantoin (3)] with D-amino acid oxidase and catalase. After the e.e. of the remaining L-6-hydroxynorleucine had risen to >99%, the reductive animation procedure was used to convert the mixture containing 2-keto-6-hydroxyhexanoic acid and L-6-hydroxynorleucine entirely to L-6-hy-droxynorleucine with yields of 91-97% and e.e. of >98%. Sigma porcine kidney D-amino acid oxidase and beef liver catalase or Trigonopsis variabilis whole cells (source of oxidase and catalase) were used successfully for this transformation [22],... 

The characterization of immobilized invertase was carried out, and the technique was successfully coupled to the catalytic activity determination of immobilized cells [59]. Similarly, the results of this technique were useful in the selection of Trigonopsis variabilis strains for high cephalosporin-transforming activity... 

Gemeiner et al. (1993) presented a similar method for the direct determination of catalytic properties of immobilized cells. Cephalosporin C transforming Trigonopsis variabilis were immobilized by three different methods, filled into a column and set into the ET. After thermal equilibration, Cephalosporin C solutions (0.1-50 mmol/1) were continously pumped through the ET until steady-state heat production was obtained. Again, the ET was shown to be suitable for a rapid and simple estimation of the kinetic properties of immobilized cells. Microkinetic factors such as mass transfer were taken into account (Stefuca et al. 1994). Thus, ET measurements allow us to obtain intrinsic data, even from immobilized cells. Moreover, the data can be applied to optimize biocatalyst design and bioreactor models (Gemeiner et al. 1996). 

Fig. 5. Correlation between heat response and reaction rate of cephalosporin C transformation by immobilized D-amino acid oxidase of Trigonopsis variabilis. Enzyme immobilization techniques entrapment in polyacrylamide gel ( ), cells cross-linked with glutaraldehyde ( ), cells entrapped in polyacrylamide gel (a) [28]...

This approach was used in the study of the properties of D-amino acid oxidase isolated or fixed in cells of Trigonopsis variabilis and entrapped in calcium pectate or polyacrylamide gel [28]. The approach of a differential reactor (low enzyme activity in the packed bed) was applied. The experimental thermometric data, ATr, were transformed to reaction rates, vobs, according to Eq. (21), whereas parameter a was determined by the calibration shown in Fig. 5. The data were described by the equation... 

The operational stability of Trigonopsis variabilis cells with D-amino acid oxidase activity, entrapped in standard and hardened ionotropic gels, was also investigated by means of the FMC [39]. The activity of the biocatalyst packed in the FMC column was continuously monitored by the FMC signal measurement... 

Fig. 13. Operational stability of D-amino acid oxidase fixed in cells of Trigonopsis variabilis CCY 15-1-3 entrapped in standard (A) and hardened (a) calcium pectate gel and standard (O) and hardened calcium alginate gel ( ). The relative activity was monitored by continuous processing, with the substrate (cephalosporin C) solution in the flow microcalorimeter [39]...

Oxidative Deamination Catalyzed by Immobilized D-Amino Acid Oxidase from Trigonopsis variabilis (E.C. 1.4.3.3) [40 421... 

D-Amlno Acid Oxidase Origin Trigonopsis variabilis... 

D-Arnino acid Oxidase, immobilized Origin Trigonopsis variabilis Fluka... 

Growing cells of Trigonopsis variabilis (DSM 70714) were found to reduce the acyclic chiral acetylsilane vac-111 enantioselectively to give the diastereomeric optically active (l-hydroxyethyl)silanes (R,R)-228 and (S,R)-228 (yield of reduction product 50%, enantiomeric purity 90 [(R,R)-228] and 94% ee [(S,R)-228], respectively)285,286. Both the yield and the enantiomeric purity of the products could be significantly improved by using resting free cells (yield 74%, enantiomeric purity of both diastereomers 96% ee substrate concentration 0.35 g/1, 37 °C)282. The optically active silanes (R,R)-228 and (SyR)-118 can be separated by chromatography on silica gel without a noticeable decrease in yield. 

By analogy to the biotransformation of rac-221, the structurally related acetyldisilane rac-229 and the acetylsilane rac-231 were also reduced enantioselectively using resting free cells of Trigonopsis variabilis (DSM 70714)282,287. The conversion of rac-229 leads to a mixture of the optically active disilanes (R,R)-230 and (S,R)-230 (yield 75%, enantiomeric purity of both diastereomers >98% ee) and the transformation of rac-231 leads to a mixture of the optically active silanes (R,R)-232 and (S,R)-232 (yield 72%, enantiomeric purity of both diastereomers 94% ee). These reactions were carried out at 37 (rac-229) and 44 °C (rac-231), respectively the substrate concentrations used were 0.53 g/1. Especially remarkable is the biotransformation of the disilane rac-229 which could be realized without a noticeable degree of hydrolytic cleavage of the Si-Si bond. 

L-6-hydroxynorleucine with yields of 91 to 97% and ee > 99%. Sigma porcine kidney D-amino acid oxidase and beef liver catalase or Trigonopsis variabilis whole cells (source of oxidase and catalase) were used successfully for this transformation. 

The first DAAO studied mechanistically was from pig kidney (pkDAAO) many kinetic and mechanistic studies have been performed on this enzyme. More recently, yeast DAAOs from Rhodotorula gracilis (RgDAAO) and Trigonopsis variabilis (TvDAAO) have also been studied. Each has different substrate specificities. The best substrate for pkDAAO is D-proline, followed by hydrophobic and neutral amino acids. Positively charged amino acids are bad substrates, while negatively charged D-amino acids are not substrates.In contrast, methionine and valine are the best substrates for RgDAAO. ... 

L-methionine DL-methionine + Asp a-keto-7-methylthiobutyric acid + NH4 + formic acid D-amino acid oxidase + transaminase Phe dehydrogenase + formate Trigonopsis variabilis Sporosarcina ureae 195... 

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