Proline mutants

The one-point mutated ALS except for the mutation of serine at position 627 to isoleucine exhibited a high resistance to the SU herbicide, chlorsulfuron. On the contrary, the resistance level of these mutated ALS s to the IM herbicide, imazaquin, was lower than that of chlorsulfuron. The mutation of proline at position 171 to alanine and histidine did not confer resistance to imazaquin. On the odier hand, the resistance level of die proline mutated ALS s to the PC herbicides was moderate between diose of chlorsulfuron and imazaquin. These results were correlated to the cross-resistance pattern of the proline-mutated ALS of K. scoparia as already described. From these results, it is considered that rice mutated recombinant ALS s, especially the proline mutants, are useful as resistant enzyme models for the herbicide resistance management at newly developed or developing ALS-inhibiting herbicides. We are now preparing other kinds of proline mutants to confirm this idea. 

Fig. 3. (A) Model of the proposed pore forming part of K channel subunits. Segments S5 and S6 are possibly membrane-spanning helices. The helices are connected by a hydrophobic segment H5 which may be tucked into the lipid bilayer [48]. H5 is flanked by two proline residues P. Adjacent to these proline residues are amino acid side chains ( ) important for external TEA binding [45,46]. Approximately halfway between these two proline residues are amino acid side chains ( ) affecting internal TEA binding [46,47] and K channel selectivity [48]. (B) Mutations are indicated which affect in Shaker channels external TEA (TEAe) or internal TEA (TEA,) binding. Concentrations of TEA for half block of the wild-type and mutant K channels are given at the right-hand side of the corresponding sequence. Data have been compiled from [45-47].

Hamase, K., Inoue, T., Morikawa, A., Konno, R., Zaitsu, K. (2001). Determination of free d-proline and D-leucine in the brains of mutant mice lacking D-amino acid oxidase activity. Anal. Biochem. 298, 253-258. 

A related fibril model for A/ o was proposed based on scanning proline mutagenesis (Williams et al, 2004) and molecular modeling (Guo et al., 2004). This model proposes that residues 15-21, 24-28, and 31-36 form 3 /-strands, with 2 intervening turns formed by residues 22-23 and 29-30 (Fig. 17G). Residues 17 and 34 are placed in close proximity, as double cysteine mutants at these positions form disulfide bonds on oxidation after fibrillization (Shivaprasad and Wetzel, 2004). Since fibrils with this triangular cross section would not be expected to show an H0-A... 

L-Pro <3, 4, 5> (<3> enzyme from strain PAOl 5mM, 50% inhibition, complete inhibition at 30 mM, noncompetitive. Strain PAO 879, a proline-auxo-troph mutant lacks a proline-inhibitable y-glutamyl kinase [5] <4> 150 = 0.08 mM, at room temperature. At low temperatures the inhibition switches over into allosteric activation and the biosynthesis of proline is started [7] <4> feedback-inhibition [8]) [5, 7, 8, 10]... 

CI2 was used in the last chapter to exemplify the basic kinetics of two-state reactions. The small fraction that folds slowly because of cis —> trans peptidyl-proline isomerization is ignored in the following discussion. CI2 folds according to first-order kinetics from a relatively open denatured state, with a half-life of some 10 ms.25 Some mutants fold 10 times faster. 

Substitute the amino acid at position 46 of object wt with a proline (P). mutate sequence wt 5 E mutant2 mutate sequence mutant2 32 P mutants mutate sequence mutant3 47 L mutant4... 

Monoclonal antibody DO-11 recognizes two adjacent peptides (38 and 39) in the PEPSCAN series, localizing the minimum epitope to the 10 amino acids, 181 arginine to 190 proline. The epitope for this antibody lies in the central part of the molecule, the conserved domain IE at the surface of the mutant p53 antigen. This antibody completely fails to immunoprecipitate p53 in the wild-type conformation (Vojtesek et al., 1995). 

---