Reaction translocation reactions

The modified elongation factor reacts normally with GTP, but the complex so formed is unable to participate in translocation. A concentration of the toxin in the cytoplasm of 10 8 M is sufficient to promote the fatal reaction. The reaction with diphthamide parallels that of cholera toxin (Box 11-A). 

The biochemical basis of CAM-induced stimulation of Ca2+-ATPase activity in carrot cells was studied further by determining the parameters of the Ca2+-translocating reaction of the enzyme in the presence and absence of exogenous CAM, using EGTA-treated plasma membrane [45], The affinity of Ca2+-ATPase for Ca2+ was considerably increased by... 

The translocation reaction in E. coli. The translocation reaction occurs immediately after peptide synthesis. It involves displacement of the discharged tRNA from the P site and concerted movement of the peptidyl-tRNA and mRNA so that the peptidyl-tRNA is bound to the P site and the same three nucleotides in the mRNA. The A site is vacated and ready for the addition of another aminoacyl-tRNA. Translocation in eukaryotes is similar except that the EF-2 factor is involved instead of the EF-G factor. 

Initiation factors contribute to the ribosome complex with the messenger RNA and the initiator methionyl-tRNA. Elongation factors assist the binding of all the other tRNAs and the translocation reaction that must occur after each peptide bond is made. Termination factors recognize a stop signal and lead to the termination of polypeptide synthesis and the release of the polypeptide chain and the messenger from the ribosome. 

The antibacterial action of erythromycin may be inhibitory or bactericidal, particularly at higher concentrations, for susceptible organisms. Activity is enhanced at alkaline pH. Inhibition of protein synthesis occurs via binding to the 50S ribosomal RNA. Protein synthesis is inhibited because aminoacyl translocation reactions and the formation of initiation complexes are blocked (Figure 44-... 

Synthesis of bridged azabicyclic compounds using radical translocation reaction followed by cyclization has been reported [95JCS(P1)1801]. Treatment of bromoamide 126 with... 

Translocation, however, requires the input of energy (again, in the form of GTP) with the participation of the elongation factor EF-G. The translocation reaction moves the peptidyl-tRNA from the A-site to the P-site. The uncharged tRNA is removed from the P-site (it remains bound at an Exit or E-site for another cycle of elongation), while the ribosome and mRNA move relative to each other. This is shown in Figure 11-8. 

Protein synthesis is an energy-intensive process. High-energy phosphate bonds are expended for each peptide bond formed. One high-energy bond is consumed when an amino acid is activated by its aminoacyl-tRNA synthetase. Delivery of aminoacyl-tRNA by EF-Tu consumes one GTP per amino acid, and the translocation reaction consumes another. 

Our success in synthesizing silyl ketals containing an aryl halide with (+)-ethyl lactate led us to explore the intramolecular radical translocation reaction (Scheme 29). The term radical translocation is described by Robertson et al. as the intramolecular abstraction of an atom (usually hydrogen) or group by a radical center this results in a repositioning of the site of the unpaired electron which can lead to functionalization at positions normally unreactive towards external reagents or whose selective modification is difficult In the most common cases the abstraction occurs at a site that is five atoms away from the radical 1,6 atom abstraction are less common, and l,n-abstractions where n > 6 are rare. This is because the shortest chain length that can accommodate the trajectory for atom abstraction contains six atoms, as in the case of the 1,5 atom abstraction. Entropic factors usually result in the failure of the process in the cases where n > 6 atoms. 

Lastly, we have to note that integral membrane proteins have been shown to have their own way to assemble, as illustrated with secondary transport proteins that drive some translocation reactions (Veenhoff et al. 2002). These authors list methods that specifically apply to membrane proteins whether studied in detergent solution or anchored to membrane. Because they are outside the scope of this review, these experimental approaches will only be enumerated into Table 3 at the exception of a very classical method (co-IP) and a cutting-edge technology (FRET/BRET). 

It is required for ion translocation reactions in stimulated neural tissue. Describe clinical manifestations of thiamine deficiency. 

C. Holm, A.R. Kimmel, and C. Londos, Mutational analysis of the hormone-sensitive lipase translocation reaction in adipocytes, J. Biol. Chem., 2003, 278, 43615— 43 619. 

Radical translocation reactions in synthesis of heterocycles 01CSR94. 

Lincomycin, which resembles erythromycin, in a dose of 500 mg t.i.d., is indicated in the treatment of serious infections due to susceptible strains of streptococci, pneumococci, and staphylococci resistant to other antibiotics. Lincomycin inhibits protein synthesis by interfering with the formation of initiation complexes and with aminoacyl translocation reactions. The receptor for lincomycins on the 50S subunit of the bacterial ribosome is a 23S rRNA, perhaps identical to the receptor for erythromycins (see also Figure 88). Thus, these two drug classes may block each other s attachment and may interfere with each other. Resistance to lincomycin appears slowly, perhaps as a result of chromosomal mutation. Plasmid-mediated resistance has not been established with certainty. Resistance to lincomycin is not rare among streptococci, pneumococci, and staphylococci. C. difficile strains are regularly resistant. 

K+, and Ca2+ To address these questions properly requires a better understanding of the three-dimensional structure of transport enzymes, the identification of principal amino acids that participate in the translocation reaction, and an appreciation of the protein molecular dynamics that contribute to ion binding (and release) and movement in the translocation domain. 

Allylation of P-oxy-o-iodoanilides. Generation of an a-radical is via a radical translocation reaction. The allylation is subject to 1,2-asymmetric induction, giving predominantly the anti products. 

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