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At least 19 recordsLinked to original sources
PubMed1979

Regulation of the biosynthesis of aminoacyl-transfer ribonucleic acid synthetases and of transfer ribonucleic acid in Escherichia coli. VI. Mutants with increased levels of glutaminyl-transfer ribonucleic acid synthetase and of glutamine transfer ribonucleic acid.

Spontaneous revertants of a temperature-sensitive Escherichia coli strain bearing a thermolabile glutaminyl-transfer ribonucleic acid (tRNA) synthetase have been selected for growth at 45 degrees C. Among 10 revertants still containing the thermolabile enzyme, 2 interesting strains were found. One strain has a fivefold elevated level of the thermolabile glutaminyl-tRNA synthetase; the genetic locus, glnR, responsible for this effect maps at min 24, far from glnS, the structural gene of the enzyme. In the other strain the levels of tRNA Gln and several other tRNAs are twice as high as in the parental strain; the locus responsible, glnU, maps at min 59.5 on the E. coli map.

Amino Acyl-tRNA Synthetases↗
PubMed1979

Regulation of the biosynthesis of aminoacyl-transfer ribonucleic acid synthetases and of transfer ribonucleic acid in Escherichia coli. V. Mutants with increased levels of valyl-transfer ribonucleic acid synthetase.

Spontaneous revertants of a temperature-sensitive Escherichia coli strain harboring a thermolabile valyl-transfer ribonucleic acid (tRNA) synthetase were selected for growth at 40 degrees C. Of these, a large number still contain the thermolabile valyl-tRNA synthetase. Three of these revertants contained an increased level of the thermolabile enzyme. The genetic locus, valX, responsible for the enzyme overproduction, is adjacent to the structural gene, valS, of valyl-tRNA synthetase. Determination (by radioimmunoassay) of the turnover rates of valyl-tRNA synthetase showed that the increased level of valyl-tRNA synthetase is due to new enzyme synthesis rather than decreased rates of protein degradation.

Amino Acyl-tRNA Synthetases↗
PubMed1976

Aminoacyl transfer RNA formation. Binding of cations to transfer RNA and its role in aminoacyl transfer RNA formation.

The role of cations (polyamines and Mg2+) in isoleucyl-tRNA formation catalyzed by purified isolecuyl-tRNA synthetase [EC 6.1.1.5] from Escherichia coli was studied. It was found that spermine, spermidine, and Mg2+ bind to tRNA and that when bound to these cations, tRNA acts as substrate of aminoacylation without requiring further cations. These findings suggest that the primary function of cations in aminoacyl-tRNA formation is to bind to tRNA to stabilize its structure, not to bind to the enzyme to activate it.

Binding Sites↗
PubMed1979

Transfer of contact sensitivity to beryllium using dialyzable leukocyte extracts (transfer factor).

Transfer factor derived from lymphocytes of donors with strong cellular immunity against beryllium was intradermally or subcutaneously injected into unprimed or subclinically primed human recipients who were patch test-negative. These recipients were challenged with beryllium at weekly intervals thereafter. Subjects who had been subclinically primed and received transfer factor either intradermally or subcutaneously showed transient patch test reactivity to the challenge. Subjects who received transfer factor but were not primed and subjects who had been primed but did not receive transfer factor showed no such conversion. This is the first demonstration of transfer of contact sensitivity in man using transfer factor, and it suggests that subclinical priming is necessary for such transfers.

Beryllium↗
PubMed1975

Carrier-mediated transfer of D-glucose in brush border vesicles derived from rabbit renal tubules. Na+-dependent versus Na+-independent transfer.

A brush border preparation from rabbit renal tubules containing a high yield of vesicles has been used to study the transfer of D-glucose through the brush border membrane. In the presence of an Na+ gradient across the vesicular membrane, the vesicles could concentrate D-glucose to a factor of 1.5, whereas in the absence of an Na+ gradient, only equilibrium with the medium was achieved. Two types of transfer could be distinguished by their requirement of Na+, their sensitivity to phlorizin and their pH optimum. The Na+-independent transfer was about 100 times less sensitive to phlorizin than the Na+-dependent path and exhibited a pH optimum between 7 and 8, whereas the Na+-dependent transfer was highest at a pH between 8 and 9. The brush border preparation could be freed of most of the contaminating material derived from the basal and lateral tubular cell membrane by a discontinuous density gradient centrifugation. It still showed both forms of transfer to a similar extent, indicating that both are located in the brush border membrane. A study of the sensitivity of D-glucose transfer to phlorizin, in the presence and absence of Na+ at different temperature, suggests a single carrier species functioning in two interchangeable conformational states with different affinities for phlorizin rather than two transfer systems working independently.

Adenosine Triphosphatases↗
PubMed1979

Transference in the rat man case: the transference in transition.

This study has concentrated on the use of the transference concept in the Rat Man case as a method for revealing repressed memories and to gain conviction about these repressed memories. In this treatment-transference model, transference interpretations focusing on the analyst are not germane, since the transferences are merely the vehicle by which memories are uncovered. Thus, Freud's transference work in 1907 revealed a transitional phase of his clinical activity soon to be supplanted by later insights into the curative aspects of transference analysis.

Child↗
PubMed1977

Rat liver proteins capable of transferring phosphatidylethanolamine. Purification and transfer activity for other phospholipids and cholesterol.

Two proteins, one in a highly purified form, have been isolated from the soluble fraction of rat liver homogenate. These proteins accelerate the transfer of labeled phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, sphingomyelin, and cholesterol from liposomes to mitochondria or erythrocyte ghosts. The fraction obtained after ammonium sulfate precipitation, gel filtration on Sephadex G-75, ion-exchange chromatography on CM-cellulose, ampholyte displacement chromatography, and heat treatment exhibited an 876-fold increase in its phosphatidylethanolamine transfer activity as compared with the postmitochondrial supernatant adjusted to pH 5.1. Isoelectric focusing on polyacrylamide gels shows a single band between pH 8.6 and 9.0. The transfer activity is abolished by trypsin, but withstands 5-min heating at 90 degrees. After heat treatment, a single major band is seen on polyacrylamide gel electrophoresis followed by two minor ones. The molecular weight of the major band is 12,500, as determined by electrophoresis on 15% polyacrylamide gels in the presence of sodium dodecyl sulfate. A molecular weight of 13,500 was calculated from molecular filtration through Sephadex G-50. The relative transfer activities toward the different phospholipids remain constant throughout the last three steps of the purification procedure in spite of the extensive change in the electrophoretic profile of the protein mixture. The cholesterol transfer activity remains unchanged after the final heat treatment as well. This indicates that all of the transfer activities are present in a single protein.

Animals↗
PubMed1977

Transfer of delayed hypersensitivity in mice to microbial antigens with dialyzable transfer factor.

Dialyzable Lawrence-type transfer factor was prepared from the spleen cells of CF1 mice inoculated with Coccidioides immitis- and Candida albicans-killed vaccines and with live Mycobacterium tuberculosis vaccine (BCG). These preparations were shown to transfer antigen-specific cell-mediated immunity to naive mice, as measured by the delayed skin test and footpad-swelling methods. Reactivity could be demonstrated when the test antigens were given 24 h after the transfer factor, but not when they were given simultaneously. Coccidioides-specific transfer factor was shown to be sensitive to Pronase and resistant to trypsin and ribonuclease. A preparation of BCG transfer factor was sensitive to snake venom phosphodiesterase.

Animals↗
PubMed1979

Investigations of 'transfer factor' activity in the transfer of immunity to Trichostrongylus axei infections in sheep.

Three investigations are described in which non-dialysed and dialysed leucocyte lysates, 'transfer factor' prepared from the blood of sheep infected with Trichostrongylus axei successfully transferred immunity to challenge infection with that parasite in susceptible lambs. Similar leucocyte lysates from parasite-free lambs failed to transfer a similar resistance to challenge infection. 'Transfer factor' treatment produced a 30--72 per cent reduction in a total worm burden compared to susceptible control lambs. In the first two investigations the donor and recipient lambs were genetically dissimilar and in the third investigation were of different breeds. The resistance transfer was considered to operate independently of immune incompetence.

Animals↗
PubMed1978

[Transfer of cellular immunity to the causative agent of coccidioidosis using the transfer factor in mice].

Experiments conducted on non-linear mice demonstrated a possibility of transfer by the intact recipient of delayed hypersensitivity by means of Lawrence'transfer-factor from mice immunized with Coccidioides immitis. The transfer factor administered 48 hours before the intranasal infection protected mice from the lethal dose of coccidioides. This indicated that in coccidioidosis it was possible to transfer delayed hypersensitivity and cellular immunity with the transfer factor.

Animals↗
PubMed1978

Raman spectra of ten aqueous transfer RNAs and 5S RNA. Conformational comparison with yeast phenylalanine transfer RNA.

Eleven native transfer RNAs have been prepared so as to maintain their Mg2+ content. Their aqueous Raman spectra show a high, relatively constant amount of order in the ribophosphate backbone, as indicated by the ratio 1.73 +/- 0.05 for I814/I1100 in all samples. Variation in the effectiveness of stacking of guanine and adenine bases is seen, though most of the transfer RNAs studied have a comparable degree of stacking to that found in phenylalanine transfer RNA from yeast, whose tertiary structure has been determined by X-ray crystallography. The spectrum of Escherichia coli 5S RNA indicates that the stacking efficiency of the guanine bases is much higher in 5S RNA than in yeast in phenylalanine transfer RNA, while that of the adenine bases is lower.

Escherichia coli↗
PubMed1977

Serial transfer of a human gene to rodent cells by sequential chromosome-mediated gene transfer.

The human hypoxanthine phosphoribosyl-transferase (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) gene (hprt) has been serially transferred to mouse cells and then to Chinese hamster fibroblasts by two cycles of metaphase chromosome isolation and incubation with recipient cells. Human metaphase chromosomes were incubated with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase, and independent colonies expressing the human species form of this gene were isolated in a selective medium. Metaphase chromosomes isolated from two of these clonal lines were incubated with Chinese hamster fibroblasts deficient in hypoxanthine phosphoribosyltransferase; five resulting independent colonies again expressed the human species of this gene. The transfer frequencies in the two cycles of chromosome-mediated gene transfer were similar (about 10(-7)). These results indicate that the transferred human chromosome fragment is closely associated with the chromosomes of the mouse A9 cells and it is probably integrated into the chromosomal DNA of the recipient cell.

Animals↗
PubMed1979

Normal values of transfer factor and transfer coefficients in healthy males and females.

A population study was performed to obtain local normal values of the transfer factor for a respiratory laboratory providing a routine hospital service. Statistical analysis of the results obtained showed similar results to those of previous investigators for the transfer factor and alveolar volume. The transfer factor was found to be dependent on height, age and sex, while the alveolar volume depended only upon height and sex. Unlike previous investigations, however, the present study showed that the transfer coefficient was the same for women as for men and was related solely to age.

Adolescent↗
PubMed1975

Adoptive transfer of experimental allergic encephalomyelitis (EAE): prevention of successful transfer by treatment of donors with myelin basic protein.

After onset of experimental allergic encephalomyelitis (EAE), guinea pigs can be effectively treated by injection with myelin basic protein (BP). In order to localize the site of action of BP, cells from sensitized donors treated with BP one, two, three, or four times after disease onset have been transferred to normal recipients. One injection of BP has no effect on ability of cells to transfer EAE. Two injections partially inhibit transfer. After the third and fourth injections the sensitized cells lose their capacity to transfer EAE. The therapeutic effect of BP previously demonstrated in actively sensitized guinea pigs must involve the specifically sensitized cells rather than the target organ.

Animals↗
PubMed1977

Photo-induced charge transfer. A critical test of the mechanism and range of biological electron transfer processes.

The vibronic coupling theory of electron tunneling between biomolecules requires that all such tunnelings involve vibronic coupling, finds temperature dependence to tunneling at finite temperatures, and predicts relatively short tunneling distances. This theory might be expected to apply to most electron transfers involved in the membrane-bound electron transfer reactions of photosynthesis and oxidative phosphorylation. This paper calculates the properties of a weak charge-transfer optical absorption band, whose predicted characteristics are a direct and simple consequence of the model that describes vibronically coupled tunneling. The new absorption band provides the basis for a critical experimental test of the constructs and parameters of the tunneling theory. If the tunneling theory is valid, the oscillator strength of such bands will be the most reliable measure of the tunneling matrix element and of the distance between the sites exchanging an electron.

Electron Transport↗
PubMedDate not supplied

1H and 13C NMR study of proton transfer in azoles. Mechanism of proton transfer in pyrazole in solutions containing bis-(acetylacetonato) nickel (II).

Proton transfer in pyrazole systems involving interaction with a paramagnetic transition metal complex has been studied with 1H and 13C NMR techniques. Kinetics of the ligand exchange in the pyrazole complex of bis-(acetylacetonato)nickel (II) has been investigated, and hyperfine coupling constants for the interaction of the nickel unpaired electron with the ligand nuclei in the complex have been determined. Catalytic admixtures of bis-(acetylacetonato)nickel (II) are shown to modify the mechanism of the proton transfer in pyrazole. The spectral data are discussed in terms of outer-sphere coordination and cooperative proton transfer effects.

Chemical Phenomena↗
PubMed1977

Application of radiationless energy transfer for distance measurements across membranes. Transition Probabilities for radiationless energy transfer within several assemblies of donors and acceptors at stationary distances.

For several 2-or 3-dimensional configurations of stationary donors and acceptors on or near a spherical membrane shell the transition probabilities for radiationless energy transfer are calculated, using Förster's approximation obtained for Coulombic dipole-dipole interaction of the transition moments. It turns out that the difference in the refractive indices for membrane (lipid) and bulk phase (water) has only a small influence on the transition probabilities. Furthermore, the curvature of biological cell surfaces can be neglected, but affects the energy transfer across small vesicles. The ratio thickness/radius of small vesicles can be determined by measuring fluorescence quenching of excited donors by acceptors on the other side of the membrane.

Energy Transfer↗