Mutants isomerase

Ag-isomerase leading to depletion of ergosterol and accumulation of an unplanar sterol ignosterol. With the inhibition of two steps in the same pathway, a natural synergistic effect is built into the molecule so that the risk of appearance of resistant mutants is low and efficacy high. 

Isomerisation of 15-c/5-phytoene to the all-/ra x configuration must occur during the desaturation steps, since most desaturated carotenes are in the all-trans form. The CRTI type desaturases appear to be able to carry out this isomerisation themselves (Fraser et al, 1992 Bartley etal, 1999), but mutants of PDS/ZDS-type organisms accumulate cis isomers of unsaturated carotenes, suggesting the presence of a separate isomerase (Clough and Pattenden, 1983 Ernst and Sandmann, 1988). Three recent publications have reported the cloning of a carotene isomerase (CrtlSO) from tomato (Isaacson et al, 2002), Arabidopsis (Park et al, 2002) and Synechocystis 6803 (Breitenbach... 

Table VI. Effect of Diethylpyrocarbonate (DEPC) on Thermoanaerobe Glucose Isomerase Activity of the Wild-Type and Mutant Enzymes ...

Figure 6. Plot of relative log of apparent versus pH for Ghiioi mutant (filled circles) and wild-type (open circles) xylose isomerases. Apparent values at different pH were determined from a Lineweaver-Burk plot. The scale of relative log Vmax pp indicates the fraction of each experimental value at different pH relative to the maximal value. Both enzymes were stable under the assay conditions used. Reprinted with permission from ref. 22. Copyright 1990 American Society for Biochemistry and Molecular Biology.

HV032 Reuber, S., B. Jende-Strid, V. Wray, and G. Weissenbock. Accumulation of the chalcone isosalipurposide in pri- HV042 mary leaves of barley flavonoid mutants indicates a defective chalcone isomerase. Physiol Plant 1997 101(4) ... 

Borchert TV, Pratt K, Zeelen JP, Callens M, Noble MEM, Opperdoes FR, Michels PAM, Wierenga RK. Overexpression of trypanosomal triosephosphate isomerase in Escherichia coli and characterization of a dimer-interface mutant. Eur JBiochem 1993 211 703-710. 

Suppose that you are seeking bacterial mutants with altered triose phosphate isomerase (TPI). The organism of interest is known to use the glycolytic pathway with the production of lactate. 

The isolation of mutants in S. typhimurium by Rick and Osborn (11,12) and mutants in E. coli by Nishijima and Raetz (44) that accumulate the Lipid A precursor indicate that KDO synthesis and Lipid A synthesis are not coordinately controlled. The initial steps in the synthesis of the Lipid A precursor are totally unknown. The temperature sensitive mutants of E. coli isolated by Nishijima and Raetz (44) that are defective in phosphaditylglyc-erol phosphate synthesis at 42°C and accumulate the Lipid A precursors indicate that there is some relationship between the synthesis of phosphatidylglycerol and LPS. The reasons for the acu-cumulation of the Lipid A precursors in this E. coli mutant are not obvious. We have shown that CDP-diglyceride, one of the substrates for phosphatidylglycerol phosphate synthesis, is an inhibitor of D-arabinose-5-phosphate isomerase with an 1 value... 

E. A. Komives, and G. A. Petsko, Crystal structure of the mutant yeast triosephos-phate isomerase in which the catalytic base glutamic add 165 is changed to aspartic add, Biochemistry 1994,33, 2824—2829. 

MR Mo watt, EC Weinbach, TC Howard, TE Nash. Complementation of an Escherichia coli glycolysis mutant by Giardia lamblia triosephosphate isomerase. Exp Parasitol 78 85-92, 1994. 

G. M., Szabo, B., Wagner, G., Kovari, Z., Horanyi, M., Baroti, K., Martial, J. A., Hollan, S., Ovadi, J. Distinct behavior of mutant triosephosphate isomerase in hemolysate and in isolated form molecular basis of enzyme deficiency. Blood 2001, 98 3106-3112. 

Lysine Glucose Investigation of metabolic fluxes in phosphoglucose isomerase mutants [108]... 

Kruckeberg, A. L., Neuhaus, H. E., Feil, R.. Gottlieb, L. D., and Stitt, M. 1989. Decreased-activity mutants of phosphoglucose isomerase in the cytosol and chloroplast of Clarkia xantiana Impact on mass-action ratios and fluxes to sucrose and starch and estimation of flux control coefficients and elasticity coefficients. Biochem. J. 261, 457-467. 

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