scholarly journals Compartmentation of free amino acids for protein biosynthesis. Influence of diurnal changes in hepatic amino acid concentrations of the composition of the precursor pool charging aminoacyl-transfer ribonucleic acid

1977 ◽  
Vol 162 (2) ◽  
pp. 257-266 ◽  
Author(s):  
A Vidrich ◽  
J Airhart ◽  
M K Bruno ◽  
E A Khairallah
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Protein Biosynthesis ◽  
Specific Radioactivity ◽  
Diurnal Changes ◽  
Unequal Distribution ◽  
Precursor Pool ◽  
Aminoacyl Transfer ◽  
Amino Acid Concentrations

To investigate further the mechanisms by which amino acids are segregated for protein biosynthesis, the distribution of a pulse of [3H]valine was monitored in hepatic amino acid pools at seven intervals in the diurnal cycle of meal-fed rats. Although each condition was characterized by a unique balance between intracellular and extracellular valine, in every case the specific radioactivity of valyl-tRNA at steady state was higher that that of intracellular valine but below the extracellular value. Further, the specific radioactivity of the valyl-tRNA could be accurately predicted if extracellular and intracellular valine were combined in proportions specified by the transmembrane concentration gradient. These observations not only substantiate our earlier conclusions that the amino acids used for protein synthesis do not originate exclusively from either the intracellular or extracellular pools, but also strengthen our theory that the membrane transport system is the physical basis for such compartmentation. On the basis of these data we present a method for measuring the specific radioactivity of the precursor pool for protein biosynthesis in cases where the actual isolation of the aminoacyl-tRNA is not technically feasible, and also suggest a theoretical basis for interpreting the unequal distribution of both total and [3H]valine between intracellular and extracellular fluids.

scholarly journals Preparation of polyribosome aminoacyl-transfer ribonucleic acid from the muscle of chick embryos.

1975 ◽  
Vol 147 (3) ◽  
pp. 473-477 ◽  
Author(s):  
M Nwagwu
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sodium Dodecyl Sulphate ◽  
Ribonucleic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sodium Dodecyl ◽  
Specific Radioactivity ◽  
Chick Embryos ◽  
Aminoacyl Transfer

A procedure for preparing polyribosome aminoacyl-tRNA free from contamination by supernatant aminoacyl-tRNA and free amino acids is described. Important features of the procedure are the use of acidic buffers to help protect the amino acid-tRNA linkage and the inclusion of sodium dodecyl sulphate, to inhibit ribonuclease activity. The specific radioactivity of polyribosome aminoacyl-tRNA is high within 30s and reaches a maximum in 2 1/2 min, well ahead of polyribosome peptides which, as described by Herrmann et al. (1971), attain maximum specific radioactivity in about 10 min.

Effect of fertilization on free amino acid concentrations in black spruce and jack pine containerized seedlings

1987 ◽  
Vol 17 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Y. T. Kim ◽  
C. Glerum ◽  
J. Stoddart ◽  
S. J. Colombo
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Black Spruce ◽  
Jack Pine ◽  
Foliar Nitrogen ◽  
Containerized Seedlings ◽  
High Concentrations ◽  
Amino Acid Concentrations

Greenhouse-grown black spruce and jack pine container seedlings were fertilized weekly with a 20–8–20 fertilizer at four concentrations during the fall. Seedlings were sampled when 23 weeks old towards the end of the greenhouse cultural period to determine the effect of fertilization on the free amino acid concentrations. All amino acids, except tryptophan, showed significant increases in concentration with higher levels of fertilizer; the concentration of tryptophan decreased with increasing fertilizer concentration. Amino acids with the highest concentrations in black spruce were arginine, glutamic acid, and proline, while in jack pine, besides these three, aspartic acid and glutamine were also found in high concentrations. Black spruce had significantly higher amino acid concentrations than jack pine. The concentrations of certain free amino acids may be more sensitive indicators of seedling nitrogen status than total foliar nitrogen.

EFFECT OF CORTISOL TREATMENT ON FREE AMINO ACID LEVELS IN RATS

1973 ◽  
Vol 59 (1) ◽  
pp. 57-63 ◽  
Author(s):  
W. DE LOECKER ◽  
M. L. STAS
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Protein Turnover ◽  
Free Amino Acids ◽  
Free Amino ◽  
Experimental Period ◽  
Amino Acid Levels ◽  
Amino Acid Concentrations

SUMMARY Changes in the concentrations of free amino acids in intracellular fluids and blood plasma were measured in rats treated with cortisol. Increasing age raised the concentrations of free amino acids in plasma, while in liver, with the exception of glycine and alanine, decreased concentrations were observed. Cortisol treatment reduced free amino acid levels in plasma and liver which suggested a progressive catabolism of body proteins and increased protein synthesis in the liver. In skeletal muscle of control rats the free amino acid concentrations increased during the experimental period. Cortisol increased the concentration of certain amino acids and decreased that of others due to an increased protein turnover in muscle.

scholarly journals The specific radioactivity of the precursor pool for estimates of the rate of protein synthesis (Short Communication)

1973 ◽  
Vol 134 (4) ◽  
pp. 1127-1130 ◽  
Author(s):  
Edward B. Fern ◽  
Peter J. Garlick
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Short Communication ◽  
Specific Radioactivity ◽  
Precursor Pool

Infusion of rats with [U-14C]glycine resulted in labelling of glycine and serine in tissue proteins. The pattern of labelling in protein more nearly resembled that of the free amino acids in the tissue than in the plasma.

ION EXCHANGE CHROMATOGRAPHY OF THE FREE AMINO ACIDS IN THE PLASMA OF INFANTS UNDER 2,500 GM AT BIRTH

PEDIATRICS ◽  
1970 ◽  
Vol 45 (4) ◽  
pp. 606-613
Author(s):  
Johanne C. Dickinson ◽  
Herman Rosenblum ◽  
Paul B. Hamilton
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ion Exchange ◽  
Free Amino Acids ◽  
Free Amino ◽  
High Sensitivity ◽  
Exchange Chromatography ◽  
Chromatographic Technique ◽  
The Individual ◽  
Amino Acid Concentrations

The free amino acids in the plasma of 46 infants who were under 2,500 gm at birth were determined by an ion exchange chromatographic technique of high sensitivity and resolution. Ninety-two plasma samples were collected from the 46 infants on different days after birth, and the data for 23 amino acids plus taurine and ethanolamine were summarized and compared with newborn, full-term and adult levels. In 16 cases tyrosine levels were high; these values are listed separately. With respect to the remaining amino acids, many showed marked changes during the first few postnatal days; but, by the end of the first week, stable patterns had developed. The decrease or increase of the individual amino acid concentrations in these infants compared to infants with birth weights over 2,500 gm and to the adult was not great and seemed to be characteristic for each amino acid. Attention was drawn to the technical details of preparing and analyzing physiological fluids which would minimize the changes in amino acid concentrations resulting from improper handling.

scholarly journals The rate of protein degradation in developing brain. Methodological considerations

1982 ◽  
Vol 208 (3) ◽  
pp. 659-666 ◽  
Author(s):  
D S Dunlop ◽  
D M McHale ◽  
A Lajtha
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Free Amino ◽  
Specific Radioactivity ◽  
Pulse Labelling ◽  
Brain Protein ◽  
Degradation Rates ◽  
Breakdown Rates ◽  
Methodological Considerations

Recently we reported that the rate of protein breakdown decreases during development. Breakdown rates were calculated from the rates of protein synthesis and the changes in brain protein content with age. A different study, measuring breakdown by monitoring the loss of label from brain protein after an H14CO3- pulse, came to the opposite conclusion: that the rate of breakdown is low in immature brain and increases during development. We have now investigated some of the factors (the distribution of label in protein and the potential for recycling) that might introduce errors into these measurements. The specific radioactivities of both protein-bound and free amino acids were determined in the brains of young rats several days after an intraperitoneal pulse of H14CO3-. For a number of amino acids the specific radioactivity of the free amino acid is high compared with that of the protein-bound amino acid, and therefore recycling could result in an underestimate of the degradation rate. Because glutamic acid had a relatively low specific-radioactivity ratio, [1-14C]glutamic acid was used in a pulse-labelling experiment to measure degradation. The rate so obtained, 0.6% . h-1, is twice the rate found with H14CO3- labelling (based on total protein-bound radioactivity). Insofar as recycling is a possible complication, 0.6% . h-1 may be a minimum value. Although somewhat higher degradation rates are found after labelling with an intracranial pulse, which was considered as a possible route to limit recycling, there are difficulties in interpreting these data.

Effect of protein precipitating agents on the recovery of plasma free amino acids

1991 ◽  
Vol 71 (3) ◽  
pp. 953-957 ◽  
Author(s):  
G. W. Sedgwick ◽  
T. W. Fenton ◽  
J. R. Thompson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Trichloroacetic Acid ◽  
Protein Concentration ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Amino Acid Concentrations ◽  
Plasma Free Amino Acids

The effect of the protein precipitants acetone, acetonitrile, perchloric acid and trichloroacetic acid on free amino acid concentrations in supernatants from ovine plasma and bovine serum albumin solutions was determined. The organic precipitants decreased (P < 0.05) free amino acid concentrations in a protein concentration dependent manner while the acid precipitants had no effect. Key words: Amino acids, protein precipitating agents

Incorporation of carbon atoms from glucose into free amino acids in brain under normal and altered conditions

1970 ◽  
Vol 48 (3) ◽  
pp. 228-235 ◽  
Author(s):  
Y. Yoshino ◽  
K. A. C. Elliott
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Acid Level ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
Aminobutyric Acid ◽  
Aminooxyacetic Acid

The time course of entry of radioactive carbon from intravenously administered [U-14C]-glucose into free amino acids in the brains of rats has been studied using an automatic amino acid analyzer coupled through a flow cell with a scintillation counter. Radioactivity appeared rapidly in alanine, aspartic acid, glutamic acid, glutamine, and γ-aminobutyric acid as previously shown, and in an unknown ninhydrin-positive substance present in very small amount. Urea, serine, and glycine became slightly radioactive. Four hours after giving the radioactive glucose, the specific activity in all soluble substances was low. In pentobarbital anesthesia, specific radioactivity was increased in alanine and decreased in γ-aminobutyric acid, aspartic and glutamic acids, and glutamine. A high proportion of radioactivity remained in glucose. Under hypoxia, alanine increased in amount but decreased in specific activity, and the specific activities of the other strongly labelled amino acids decreased. The proportion of the total radioactivity found in glucose and lactate increased. During picrotoxin and pentylenetetrazol convulsions, changes occurred which were similar to those under hypoxia. After aminooxyacetic acid administration, the well-known great increase in γ-aminobutyric acid level was found to be accompanied by a decrease in glutamate and also in aspartic acid and alanine, indicating inhibition of the three transaminases concerned. The previously observed brief rapid postmortem increase in the amount of γ-aminobutyric acid was confirmed; alanine also increased briefly but no other amino acid did so. The increased γ-aminobutyric acid had the same specific radioactivity as the original but the extra alanine was less radioactive than the original. When the γ-aminobutyric acid level had been increased by administration of aminooxyacetic acid, the rapid postmortem increase did not occur.

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