Puromycin action

Sarma et al.199 reported that the tube-feeding of L-tryptophan (10 min) after puromycin treatment (20 min) had a corrective effect on the state of hepatic polyribosomes and on protein synthesis. In another study, Sidransky et al.188 reported that pretreatment with L-tryptophan (0.5 h) before puromycin (20 min before kill) improved hepatic polyribosomal aggregation and protein synthesis. Thus, L-tryptophan was preventative as well as curative in regard to puromycin action. 

One type of fatty liver that has been smdied extensively in rats is due to a deficiency of choline, which has therefore been called a lipotropic factor. The antibiotic puromycin, ethionine (a-amino-y-mercaptobu-tyric acid), carbon tetrachloride, chloroform, phosphorus, lead, and arsenic all cause fatty liver and a marked reduction in concentration of VLDL in rats. Choline will not protect the organism against these agents but appears to aid in recovery. The action of carbon tetrachloride probably involves formation of free radicals... 

Homocitrullylaminoadenosine(LXXVlII) [349] also inhibits protein synthesis, presumably in the same way that puromycin does [350]. A similar mode of action has been suggested for lysylaminoadenosine (LXIX) [351,352]. 

Figure 23-10 Structure of translation inhibitors, and the mechanism of action of puromycin. (From Lehninger, A.L., Nelson, D.L., and Cox, M.M. Principles of Biochemistry, 2nd ed. New York Worth, Figure 26-34. Reprinted with permission.)...

Compare the relative level of 3H-poly-Phe present in vial 11 compared to that in vial 16. Explain your results in terms of the components that were present in these two reactions, and your knowledge of the mechanism of action of puromycin. 

Inhibition of protein synthesis by aminoglycoside antibiotics, especially by streptomycin, is bactericidal (rev.46)). The antibiotic binds to the smaller ribosomal subunit and leads to the formation of abortive initiation complexes of ribosomes, streptomycin and amino acyl tRNA which progressively trap ribosomes in the form of such biologically irreversible complexes. When protein synthesis is prematurely terminated by puromycin and ribosomes are thus made available for reinitiation of de novo protein biosynthesis, the bactericidal action of streptomycin is accelerated47). Destruction of ribosomes under the influence of primaquine operationally also results in non-occurrence of protein synthesis and in a marked bactericidal effect48, 49 ... 

Figure 29.34. Antibiotic Action of Puromycin. Puromycin resembles the aminoacyl terminus of an aminoacyl-tRNA. Its amino group joins the carbonyl group of the growing polypeptide chain to form an adduct that dissociates from the ribosome. This adduct is stable because puromycin has an amide (shown in red) rather than an ester linkage.

Mechanism of action of puromycin. Puromycin is able to enter the ribosome A site and function as an aminoacyl tRNA analogue, resulting in polypeptide chain termination in both... 

Tata JR. Inhibition of the biological action of thyroid hormones by actinomycin D and puromycin. Nature 1963 197 1167-1168. 

In washed brain slices, an in vitro model for the evaluation of effects of membrane-bound enzymes on enkephalin hydrolysis, the main hydrolysis products have been identified as Tyr and Tyr-Gly-Gly. The formation of Tyr-Gly-Gly is dependent on the action of enkephalinase and is reduced in the presence of thiorphan (an enkephalinase inhibitor). In the presence of bestatin (a general aminopeptidase inhibitor), the formation of Tyr is reduced Tyr is also reduced, to a lesser extent, in the presence of puromycin (an aminopeptidase Mil inhibitor). In the presence of thiorphan the formation of Tyr increases whereas in the presence of bestatin there is an increase in formation of Tyr-Gly-Gly. The level of Tyr-Gly in this model is low and is unaffected by either thiorphan or bestatin indicating that the action of DAP is unimportant. Recovery of endogenous enkephalins released by depolarisation of brain slices is enhanced in the presence of thiorphan or bestatin and is complete when both inhibitors are present. This does not occur in the case of puromycin or captopril (an ACE inhibitor) [31]. 

The mechanism of action of blasticidin S has been studied for more than 20 years. In the 1960s, it was recognized that blasticidin S stimulates T-factor-dependent binding of phenylalanine tRNA to ribosomes (96), and that it inhibited the effects of puromycin in a manner similar to chloramphenicol (97). Blasticidin S binds strongly to the SOS sub-... 

Pestka S. Studies on the formation of transfer ribonucleic acid-ribosome complexes. VIH. Survey of the effect of antibiotics on N-acetyl-phenylalanyl-puromycin formation Possible mechanism of chloramphenicol action. Atch Biochem Biophys 1970 136 80-88. 

In addition, analogous experiments were carried out with puromycin (0.03 milligram per milliliter, as dihydrochloride), under conditions of repression or physiological derepression. In this case, no effect on the differential rates of formation of the transaminase, argininosuccinase, or acetylornithinase was observed. These negative findings with puromycin, on the one hand, indicate that the results with the 30 S inhibitors streptomycin and tetracycline are not nonspecific consequences of ribosomal inhibition or lowered growth rate and, on the other hand, would seem to reflect the differences in mode of action between these two inhibitors and puromycin. (A review of the mode of action of ribosomal inhibitors has recently been prepared by Pestka [104].)... 

Caffeine and puromycin also stimulate the conversion of phosphorylase (a) to phosphorylase (b), probably by interfering with the breakdown of the 3, 5 -cyclic adenosine nucleotide. A diesterase capable of splitting the cyclic phosphate of the 3, 5 -cyclic adenosine phosphate has been found in beef heart. The effect of epinephrine on phosphorylase is important because it constituted the first explanation of a hormone s mechanism of action in molecular terms. 

The action of ammonia or amines on the epoxy sugars results in ring opening with the formation of aminodeoxy sugars or their derivatives. An interesting example is found in the conversion of D-xylose to 3-amino-3-deoxy-D-ribose, a structural component of the antibiotic puromycin (80). The transformation (see formulas on p. 392) is remarkable in that derivatives of all four D-aldopentoses are involved. 

The higher resolution studies of subunits have also revealed the mode of action of several antibiotics such as paromomycin, streptomycin, and spectinomycin, which modify the decoding function of the small subunit, and chloramphenicol, puromycin, and vernamycin, which affect peptide bond formation. 

It was considered of interest to test the possibility that puromycin and actinomycin D might interfere with the stimulating action of RF s. If so,this would signify... 

To control a possible effect of puromycin and acti-nomycin D on the release of FSH under action of FRF, pituitary halves were incubated for 2 hr with either FRF or antibiotics and FRF (18, 16), The whole experiment was done in 4 flasks and the pituitary halves were randomized in order to compare the results statistically. 

The statistical analysis of the results is recorded in the legend of Fig. 3. Puromycin diminished significantly the releasing action of FRF (compar. 3/2) but did not abolish this action (compar. 3/1). Actinomycin gave similar results. There was no significant difference between the control tissues and tissues treated with FRF but the FSH content of the tissues treated with puromycin and actino-... 

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