[Immunological study of protein biosynthesis].
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Protein Biosynthesis↗
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[Problem of protein biosynthesis].
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Protein Biosynthesis↗
[Regulatory role of amino acids in protein biosynthesis; effect of various factors].
The paper embraces data available in literature and the results of the author's investigations which show synergism and antagonism interrelations between certain amino acids in the processes of transmembrane transport, amino acylation of transfer RNA and incorporation into protein. These interrelations may lead to activation and inhibition of the protein biosynthesis. It is established that an excess of any amino acid created with its administration into the organism induces the inhibition of biosynthesis and activity of the corresponding aminoacyl-tRNA-synthetase (ARSase), while deficiency of an amino acid intensifies the biosynthesis of the corresponding ARSase. Homogeneous crystalline proteins, such as aldolase of rabbit skeletal muscles, collagen I of rat skin, globin of chicken blood and others, are used as an example to show that as a result of feeding of the amino acid excess to animals, especially against a background of protein deficiency, the biosynthesis intensity changes and proteins with other primary structure and properties are synthetized. This testifies to that amino acids being substrates in the protein biosynthesis are regulators in this process. It is established that the biosynthesis of proteins with other primary structure under conditions of complete fasting, protein deprivation, feeding of an excess of certain amino acids to animals against a background of protein deficiency, atherosclerosis and other extremal states of the organism is not a result of erroneous incorporation of amino acids but is the process of regular, specific and stable character for each state and may be predicted. The biosynthesis of the protein with other primary structure under the effect of extremal conditions is caused, apparently, by capability to the changes of the proteinsynthetizing system.
Amino Acid Sequence↗
Effect of 2-phenoxyethanol upon RNA, DNA and protein biosynthesis in Escherichia coli NCTC 5933.
The effects of concentrations of 2-phenoxyethanol of negligible bactericidal activity upon the rates of biosynthetic assimilation by Escherichia coli, of 14C-thymidine, 14C-uracil, 14C-phenylalanine and 14C-glucose, were assessed. Increasing the drug concentration from 0.05-0.4% w/v progressively increased inhibition of growth rate, measured as changes in optical density. Thymidine, uracil and glucose assimilation were inhibited to an extent similar to growth rate, whilst phenylalanine incorporation was markedly less sensitive at the lower concentrations (leads to 0.2% w/v). In addition to its previously observed roles in inhibiting oxidative phosphorylation and TCA cycle enzymes, it is suggested that 2-phenoxyethanol can exert a more direct inhibitory action upon DNA and RNA biosynthesis and possibly on protein biosynthesis.
Bacterial Proteins↗
[Role of protein biosynthesis activation in the mechanism of the negative chronotropic action of the vagus nerve and acetylcholine on the heart].
In rats, the following data were obtained: a) acetylcholine activates the rate of protein biosynthesis in auricles in vitro; b) protein biosynthesis inhibitors (actinomycine D, sarcolysine, neutral rot, tolluidine blue) weaken the negative chronotropic effect of acetylcholine and vagus on the heart; c) anabolic hormones increase the cholinergic effect on heart; d) acetylcholine induces hyperpolarization of the myocardial fibers which is prevented by actinomycine D. The activation of protein biosynthesis followed by hyperpolarization of the pacemaker cells seems to play an important role in the mechanism of negative chronotropic effect of acetylcholine and vagus on the heart.
Acetylcholine↗
[Effect of the replication of rubella virus on the protein biosynthesis of BHK 21 cell cultures].
The protein biosynthesis of BHK-21/C 13 cell cultures under the influence of multiplying rubella virus was studied by the uptake and incorporation of 14C leucine. The uptake of 14C leucine by the cells of virus-infected cultures was found to increase up to the third day after infection; no further increase was detectable on the fourth day. Control cultures maintained under the same conditions showed a similar behaviour up to the second and on the fourth day. On the third day, the virus-infected cultures exhibited significantly higher uptake than the controls. It may be that the virus infection causes damage to the cellular wall, the nature of which has yet to be elucidated. The protein incorporation of 14C leucine slightly increases in the virus-infected cultures 36 hrs after infection. This increase is not equally pronounced in the control cultures, but the differences were not significant.
Cell Line↗
Structural basis for the inhibition of protein biosynthesis: mode of action of tubulosine.
A structural model for the inhibition of protein biosynthesis was previously formulated on the basis of a topochemical analogy between the ipecac alkaloids and the glutarimide antibiotics. The structure of tubulosine satisfies the requirements of this model. The prediction that such a compound would exhibit amebicidal activity and act by selectively inhibiting the transfer reaction in protein biosynthesis is confirmed.
Alkaloids↗
Facilitation of protein biosynthesis by ginsenoside-Rb2 administration in diabetic rats.
In streptozotocin-induced diabetic rats given 10 mg/day of ginsenoside-Rb2 for 3 days, there was no significant increase in the serum protein and albumin levels, whereas a significant increase in these parameters was found in rats given the ginsenoside-Rb2 for 6 days. When the state of protein biosynthesis was determined using [14C] leucine, significantly activated protein biosynthesis was found in rats given ginsenoside-Rb2 for 3 days, indicating the presence of an activated state of protein biosynthesis prior to the evident quantitative increase.
Animals↗
An improved protein bioreactor: efficient product isolation during in vitro protein biosynthesis via affinity tag.
In vitro protein biosynthesis became a powerful technology for biochemical research. Beside the determination of structure and function in vitro selection of proteins is also of great interest. In most cases the use of a synthesized protein for further applications depends on its purity. For this purpose the in vitro production and purification of proteins with short affinity tails was established. A cell-free protein synthesis system was employed to produce bovine heart fatty acid-binding protein and bacterial chloramphenicol acetyltransferase with and without fusion of the Strep-tag affinity peptide. The quantitative removal of fusion protein during cell-free synthesis from a batch reaction and a semicontinuous flow cell-free reactor were achieved. No significant influence of the Strep-tag and the conditions during the affinity chromatography on maturation or activity of the proteins were observed. The product removal from the continuous flow cell-free reactor is still an only partially solved problem, because the use of ultrafiltration membranes has some limitations. The results document that it should be possible to avoid these limitations by introducing an affinity system.
Animals↗
[Effect of catechins and proanthocyanidins on the initial stage of protein biosynthesis].
Catechins and proanthocyanidins have been studied for their effect on initial stage of the protein biosynthesis. It has been found that (+)-catechin in all concentrations studied does not influence the intensity of t-RNA aminoacylation by 14C-glycine and 14C-arginine. Proanthocyanidins, namely, dimers B-3, B-6 and trimer C2 in the concentration of 10(-3) M completely inhibit the initial stage of the protein biosynthesis.
Animals↗
[Effect of electrostimulation of the hypothalamus on protein biosynthesis in organs of adult and aged rats].
The effect of hypothalamus electrical stimulation on total protein biosynthesis was studied in skeletal muscle, heart, liver, adrenal cortex and thyroid gland of adult rats. In adult animals hypothalamus stimulation provokes a pronounced increase in 3H-leucine incorporation into total protein of all tissues, as well as into liver chromatin proteins. No significant changes were observed in protein biosynthesis when hypothalamus of old rats was stimulated. This can serve as evidence of age-related decrease in the ability of the hypothalamus to stimulate protein synthesis in peripheral tissues.
Adrenal Glands↗
Effect of queuine on protein biosynthesis in mammalian cells.
Administration of queuine into intact cells has an affected protein biosynthesis in vivo. In C3H2K mouse kidney cells, synthesis of a protein having a molecular weight of 45,000 was prevented by addition of queuine into the culture medium. In the case of SA-1 cells, which are variant cells of mouse mammary tumor cells, a protein whose molecular weight was 95,000 and located in the cytosol of its cells was changed to a more basic protein by administration of queuine.
Animals↗
Macromolecular mimicry in protein biosynthesis.
Elongation factor Tu (EF-Tu) is a G-protein which, in its active GTP conformation, protects and carries aminoacylated tRNAs (aa-tRNAs) to the ribosome during protein biosynthesis. EF-Tu consists of three structural domains of which the N-terminal domain consists of two special regions (switch I and switch II) which are structurally dependent on the type of the bound nucleotide. Structural studies of the complete functional cycle of EF-Tu reveal that it undergoes rather spectacular conformational changes when activated from the EF-Tu.GDP form to the EF-Tu.GTP form. In its active form, EF-Tu.GTP without much further structural change interacts with aa-tRNAs in the so-called ternary complex. The conformational changes of EF-Tu involve rearrangements of the secondary structures of both the switch I and switch II regions. As the switch II region forms part of the interface between domains 1 and 3, its structural rearrangement results in a very large change of the position of domain 1 relative to domains 2 and 3. The overall shape of the ternary complex is surprisingly similar to the overall shape of elongation factor G (EF-G). Thus, three domains of the protein EF-G seem to mimic the tRNA part of the ternary complex. This macromolecular mimicry has profound implications for the function of the elongation factors on the ribosome.
Amino Acid Sequence↗
Kinetic study of the cytotoxic effect of alpha-sarcin, a ribosome inactivating protein from Aspergillus giganteus, on tumour cell lines: protein biosynthesis inhibition and cell binding.
alpha-Sarcin is a ribosome inactivating protein produced by the mould Aspergillus giganteus. The effect of this protein on eight different tumour cell lines has been studied in the absence of any agent affecting membrane permeability. The protein is cytotoxic for all the tumour cell lines considered. alpha-Sarcin modifies the cell proliferation pattern by inhibiting the protein biosynthesis of the cultured cells. No membrane damage produced by alpha-sarcin has been observed by measuring lactic dehydrogenase leakage. Alteration on the cell mitochondrial activity has not been detected upon treatment with alpha-sarcin. Differences on the extent of the protein binding to the cells have been observed by flow cytometric measurements. The kinetic analysis of the protein biosynthesis inhibition produced by alpha-sarcin reveals an alpha-sarcin concentration-dependent lag phase followed by a first order decrease of the protein synthesis rate. This parameter is dependent on the external alpha-sarcin concentration. A saturable component for the action of alpha-sarcin is also deduced from these experiments. Results are discussed in terms of the protein passage across the cell membrane as the potential rate-limiting step for the action of alpha-sarcin.
Animals↗
Protein biosynthesis in isolated human scalp hair follicles.
The present study demonstrates that protein biosynthesis can be studied in single isolated human scalp hair follicles. The matrix and the sheath are the main regions where amino acids are built in. Incorporation is linear for at least five hours. The newly synthesized proteins can be separated into a water-soluble, a urea-soluble and a urea-insoluble fraction. Product analysis has been performed on the first two fractions, revealing different protein patterns.
Electrophoresis, Polyacrylamide Gel↗
Studies on the mechanism of action of potassium iodide on thyroid protein biosynthesis.
Potassium iodide (KI) has been shown to have an antigoitrogenic action and to inhibit in vivo thyroid protein biosynthesis. Beef thyroid slices were used to clarify further the mechanism of action of KI. Incubations were performed in Krebs-Ringer-bicarbonate (KRB) buffer under 95%O2 and 5% CO2. KI caused a slight decrease in the uptake of [3H]eucine by the tissue. When labelled leucine incorporation into protein was measured it was found that 10(-6) M KI caused a marked inhibition. Increasing concentrations of KI up to 10(-3) M did not further increase this inhibition. This effect of KI was reduced by simultaneous addition of 0.5 mM KClO4 or 1 mM methylmercaptoimidazole (MMI). In several experiments it was found that equimolar amounts of thyroxine (T4) or triiodothyronine (T3) were more potent than KI in inhibiting thyroid protein biosynthesis. In double plabelled studies KI decreased [3H]leucine incorporation into thyroid soluble proteins and into immunoprecipitable thyroglobulin (T4) while it did not modify that of [14C]galactosamine. When tissue specificity was examined, KI failed to alter [3H]leucine incorporation into proteins either in the liver or in the submaxillary gland. The present results indicate that intracellular KI is necessary to exert its effect on protein synthesis, and that this effect is mediated through a organic form of iodine, probably iodothyronines. This action of KI is specific for the thyroid gland.
Animals↗
[Effect of tetrahydrocortisol-apolipoprotein A-I complex on RNA polymerase interaction with eukaryotic DNA and the rate of protein biosynthesis in hepatocytes].
A mechanism of activation of protein biosynthesis in hepatocytes was proposed as effected by the conditioned medium of nonparenchymal liver cells incubated in the presence of high density lypoproteins, cortisol, and lypopolysaccharides. It was found that the increase in the biosynthesis rate was associated with the formation of the tetrahydrocortisol-apolipoprotein A-I (THC-apoA-I) complex in macrophages, which display 5 alpha- and 5 beta-reductase activity and are constituents of nonparenchymal liver hepatocytes. Using the small-angle X-ray scattering technique, it was shown that the THC-apoA-I-eukaryotic DNA interaction may break hydrogen bonds between pairs of complementary nucleic bases and cause the formation of single-stranded DNA fragments capable of binding to DNA-dependent RNA polymerase. The interaction is highly cooperative and has a saturating mode, up to six enzyme molecules being bound per DNA molecule.
Animals↗
Extension of Watson's model for the elongation cycle of protein biosynthesis.
The scheme for the elongation cycle of protein biosynthesis is proposed based on modern quantitative data on the interactions of mRNA and different functional forms of tRNA with 70S ribosomes and their 30S and 50S subunits. This scheme takes into account recently discovered third ribosomal (E) site with presumable exit function. The E site is introduced into 70S ribosome by its 50S subunit, the codon-anticodon interaction does not take place at the E site, and the affinity of tRNA for the E site is considerably lower than that for the P site. On the other hand, the P and A sites are located mainly on a 30S subunit, the codon-anticodon interactions being realized on both these sites. An mRNA molecule is placed exclusively on a 30S subunit where it makes U-turn. The proposed scheme does not contradict to any data but includes all main postulates of the initial Watson's model (J. D. Watson, Bull. Soc. Chim. Biol. 46, 1399 (1964), and is considered as a natural extension of the later according to modern experimental data.
Models, Molecular↗