Double mutants

The Protein Data Bank PDB ID 1A71 Colby T D Bahnson B J Chin J K Klinman J P Goldstein B M Active Site Modifications m a Double Mutant of Liver Alcohol Dehydrogenase Structural Studies of Two Enzyme Ligand Com plexes To be published... 

Figure 17.4 Melting temperatures, Tm, of engineered single-, double-, and tripledisulfide-containing mutants of T4 lysozyme relative to wild-type lysozyme. The red bars show the differences in Tm values of the oxidized and reduced forms of the mutant lysozymes. The green bars for the multiple-bridged proteins correspond to the sum of the differences in Tm values for the constituent single-bridged lysozymes. (Adapted from M. Matsumura et al.. Nature 342 291-293, 1989.)...

Scheme 10.8 Biosynthesis of epothilone. Individual PKS domains are represented as circles and individual NRPS domains as hexagons. Acyl carrier proteins (ACPs) and thiola-tion domains (T) are posttranslationally modified by a phos-phopantetheinyl group to which the biosynthetic intermediates are covalently bound throughout the chain assembly. The thioesterase domain (TE) cyclizes the fully assembled carbon chain to give the 16-membered lactone. Following dehydration of Cl 2—Cl 3 to give epothilones C and D, the final step in epothilone biosynthesis is the epoxidation of the C12=C13 double bond by the cytochrome P450 enzyme P450epol<. KS ketosyn-thase KS(Y) active-site tyrosine mutant of KS AT acyltransfer-ase C condensation domain A adenylation domain ...

Figure 6 Model structure of CHMO. The FAD cofactor is shown as sticks. Mutations observed in a directed evolution study resulting in altered enantioselectivities are highlighted (spheres). " Note that a number of mutations were found in double/triple mutants and cannot be linked with certainty to the altered catalytic properties. Mutations in double/triple mutants that are on the...

An examination of mutant PKA proteins was undertaken. Phosphorylation of Thr-197 is required to activate PKA and phosphorylation of Ser-338 enhances stability of the protein. Replacement of Thr-197 and/or Ser-338 by Ala was examined to determine any conformational changes in the protein. Both single substitution mutants were expressed in Escherichia coli in similar levels to wild-type protein. However, both mutants were found to be less stable, as had been previously described. The double mutant... 

Burgering M, Boelens R, Kaptein R. Observation of intersubunit NOEs in a dimeric P22 Mnt repressor mutant by a time-shared [15N,13C] double halffilter technique. J Biomol NMR 1993 3 709-714. 

Serrano L, Bycroft M, Fersht AR. Aromatic-aromatic interactions and protein stability. Investigation of double mutant cycles. J Mol Biol 1990 218 465-475. 

Fig. 13 DNA-protein CT reactions. The DNA-bound protein, methyltransferase Hhal (mutant Q237W), flips a base out of the DNA double helix and inserts a trytophan side chain leaving the /r-stack largely unperturbed. This intercalated trytophan moiety transfers an electron to [Ru(bpy )(dppz)(phen)]3+, generated by flash quench, over 50 A away. Adapted from [164]... 

Eehner We haven t done these experiments. But we have looked in string mutants where cells arrest in G2 before mitosis 14 and in cyclinAl cyclinB double mutants where cells arrest in G2 before mitosis 15. The timing of dacapo expression in the epidermis appears to be normal in these mutants. 

Nasmyth In the yeast, most of the cleavage takes place in a Polo mutant, and the centromeres go to the poles quite normally. But the chromosomes don t fully disengage. We suspect about 10% of the Sccl may not be coming off. If you make a Pdsl /Polo double mutant (which is difficult because they are almost synthetic lethal), then it looks like there isn t much anaphase at all. But these are recent, preliminary results. 

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