Yeasts kinetics

Urban, R, Werck-Reichhart, D. H., Teutsch, G., Durst, F., Regnier, S., Kazmaier, M., and Pompon, D. (1994), Characterization of recombinant plant cinnamate 4-hydroxylase produced in yeast. Kinetic and spectral properties of the major plant P450 of the phenylpro-panoid pathway, Ear. J. Biochem., 222,843-850. 

Dynamic kinetic resolution of a-alkyl-P-keto ester was conducted successfully using biocatalysts. For example, baker s yeast gave selectively syn(2R, 3S)-product [29a] and the selectivity was enhanced by using selective inhibitor [29b] or heat treatment of the yeast [29c]. Organic solvent was used for stereochemical control of G. candidum [29d]. Plant cell cultures were used for reduction of 2-methyl-3-oxobu-tanoate and afforded antialcohol with Marchantia [29e,f] and syn-isomer with Glycine max [29f]. 

Another example of dynamic kinetic resolution is the reduction of a sulfur-substituted ketone. Thus, yeast reduction of (R/S)-2-(4-methoxyphenyl)-l, 5-benzothiazepin-3,4(2H, 5H)-dione gave only (2S, 3S)-alcohol as a product out of four possible isomers as shown in Figure 8.39c [29kj. Only (S)-ketone was recognized by the enzyme as a substrate and reduction of the ketone proceeded... 

Coe and Bessell and coworkers studied the metabolic fates of 2-deoxy-2-fluoro-D-glucose (2DFG) and related compounds by using yeast hexokinase (as a model for mammalian hexokinase), and determined the kinetic constants K and V ) of the Michaelis-Menten equation D-glucose 0.17 (K in mAf)> 1 00 (relative value, D-glucose taken as 1) 2DG 0.59 0.11, 0.85 2DFG 0.19 0.03, 0.50 2-deoxy-2-fluoro-D-mannose (2DFM) 0.41 0.05, 0.85 2-deoxy-2,2-difluoro-D-nraZ>//Jo-hexose... 

Figure 3 Comparison of the kinetics of release of reducing groups by various yeast strains grown on Pg glc medium...

The kinetic parameters of each interaction are reported in Table 1. These data show that the values of the equilibrium association constant Ka for the interaction of PGIP with the different yeast-e ressed polygalacturonases do not differ significant, but in each case they are 2 5 times lower wlien conq)ared to that of the F. moniliforme i2yme. This is probably... 

A kinetic resolution was also observed in the reduction of racemic a-ketosulphoxides 277 by fermenting yeast (equation 153). Both the starting ketones 277 and the corresponding )S-hydroxysulphoxides 278 formed have been recovered in almost enan-tiomerically pure form. 

As a third example let us consider the growth kinetics in a chemostat used by Kalogerakis (1984) to evaluate sequential design procedures for model discrimination in dynamic systems. We consider the following four kinetic models for biomass growth and substrate utilization in the continuous baker s yeast fermentation. 

The experiments described above indicate that technology is available to couple SPR with mass spectrometry. These methods should be useful for protein-protein interaction mapping. For example, immobilized proteins can be used as hooks for fishing binding partners from complex protein mixtures under native conditions. The coupling of techniques can lead not only to the rapid identification of interacting proteins but will also provide information on the kinetic parameters of the interaction. This approach should serve as an excellent complement to the use of in vivo techniques such as the yeast two-hybrid system. 

TABLE 8-1. Yeast-Mediated Kinetic Resolution of 2-Substituted Ketones via Baeyer-Villiger Oxidation... 

DePace, A. H., and Weissman, J. S. (2002). Origins and kinetic consequences of diversity in Sup35 yeast prion fibers. Nat. Struct. Biol. 9, 389-396. 

Fay, N., Inoue, Y., Bousset, L., Taguchi, H., and Melki, R. (2003). Assembly of the yeast prion Ure2p into protein fibrils. Thermodynamic and kinetic characterization. /. Biol. Chem. 278, 30199-30205. 

In addition to bistability and hysteresis, the minimal model of glycolysis also allows nonstationary solutions. Indeed, as noted above, one of the main rationales for the construction of kinetic models of yeast glycolysis is to account for metabolic oscillations observed experimentally for several decades [297, 305] and probably the model system for metabolic rhythms. In the minimal model considered here, oscillations arise due to the inhibition of the first reaction by its substrate ATP (a negative feedback). Figure 24 shows the time courses of oscillatory solutions for the minimal model of glycolysis. Note that for a large... 

Treatment of 9-(/ -D-ribofuranosyluronic acid)adenine with diphenylphosphoro-chloridate and orthophosphate or tripolyphosphate yields (62) and (63), which, although unstable, inhibit rabbit AMP aminohydrolase and pyruvate kinase, respectively, with behaviour characteristic of active-site-specific reagents.98 Adenylate kinases from several sources are inactivated by iV6-[2- and 4-fluorobenzoyl]-adenosine-5 -triphosphates, with kinetics characteristic of active-site labelling, although these compounds were without effect on yeast hexokinase and rabbit pyruvate kinase.99... 

The Truhlar group has reported an interesting theoretical study of H/D kinetic isotope effects for conversion of 2 phospho-D-glycerate to phosophoenolpyruvate catalyzed by the yeast enolase enzyme. The proton transfer step (first reaction step in Fig. 11.10) is the rate limiting step and was chosen for theoretical study. The KIE for proton/deuteron transfer is kn/kD = 3.3 at 300 K. 

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