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.

scholarly journals Utilization in vivo of glucose and volatile fatty acids by sheep brain for the synthesis of acidic amino acids

1966 ◽  
Vol 101 (3) ◽  
pp. 591-597 ◽  
Author(s):  
R M O'Neal ◽  
R E Koeppe ◽  
E I Williams
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
Sheep Brain ◽  
The Brain

1. Free glutamic acid, aspartic acid, glutamic acid from glutamine and, in some instances, the glutamic acid from glutathione and the aspartic acid from N-acetyl-aspartic acid were isolated from the brains of sheep and assayed for radioactivity after intravenous injection of [2-(14)C]glucose, [1-(14)C]acetate, [1-(14)C]butyrate or [2-(14)C]propionate. These brain components were also isolated and analysed from rats that had been given [2-(14)C]propionate. The results indicate that, as in rat brain, glucose is by far the best precursor of the free amino acids of sheep brain. 2. Degradation of the glutamate of brain yielded labelling patterns consistent with the proposal that the major route of pyruvate metabolism in brain is via acetyl-CoA, and that the short-chain fatty acids enter the brain without prior metabolism by other tissue and are metabolized in brain via the tricarboxylic acid cycle. 3. When labelled glucose was used as a precursor, glutamate always had a higher specific activity than glutamine; when labelled fatty acids were used, the reverse was true. These findings add support and complexity to the concept of the metabolic; compartmentation' of the free amino acids of brain. 4. The results from experiments with labelled propionate strongly suggest that brain metabolizes propionate via succinate and that this metabolic route may be a limited but important source of dicarboxylic acids in the brain.

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.

ENDOCRINE CONTROL OF FREE AMINO ACIDS CONTENT IN UTERINE FLUID IN PREGNANT RABBITS

1972 ◽  
Vol 70 (2) ◽  
pp. 409-416 ◽  
Author(s):  
S. Jaszczak ◽  
E. S. E. Hafez
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Blood Serum ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Amino Acid Content ◽  
Endocrine Control ◽  
Uterine Fluid

ABSTRACT Free amino acid content was measured in the uterine fluid and blood serum in the following groups of rabbits 168 h post copulation: intact; intact progesterone-treated; ovariectomized progesterone-treated; ovariectomized progesterone-oestradiol-treated; and ovariectomized without hormonal treatment. At implantation, concentration of the majority of amino acid in uterine fluid exceeded greatly that of blood serum; the difference in concentration being maximal for glycine, taurine, alanine, glutamic acid, aspartic acid, serine and threonine. Glutamine-asparagine and arginine were found in comparable quantities or were even higher in blood serum. Glycine, alanine, taurine, glutamic acid, serine and glutamine-asparagine were found in highest concentration in the uterine fluid. The level of ammonia in uterine fluid was also relatively high. Exogenous progesterone and oestradiol caused significant changes in the concentration of some amino acid. The concentration of glycine, taurine, alanine, serine, glutamic acid, aspartic acid, threonine, ½ cystine and histidine seems to be especially hormonally dependent. The results are discussed in relation to hormonal activity of corpora lutea during early pregnancy, physiological significance of free amino acids in uterine fluid and nourishment of an early embryo.

Free amino acid concentrations in needles of Norway spruce and Scots pine trees on different sites in areas with two levels of nitrogen deposition

1990 ◽  
Vol 20 (8) ◽  
pp. 1132-1136 ◽  
Author(s):  
Ann-Britt Edfast ◽  
Torgny Näsholm ◽  
Anders Ericsson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Nitrogen Deposition ◽  
Free Amino Acids ◽  
Free Amino ◽  
Aminobutyric Acid ◽  
Site Quality ◽  
Southern Sweden ◽  
Amino Acid Concentrations

The effects of nitrogen deposition and site quality on amino acid concentrations in needles of Piceaabies (L.) Karst. and Pinussylvestris L. trees were studied in two areas that represent different levels of nitrogen deposition: one area in southern Sweden and one area in northern Sweden receive, respectively, approximately 20–30 and 3 kg•ha−1•year−1 of nitrogen. On each area three site quality classes were chosen for each tree species. The site classes were chosen to represent poor, medium, and good sites typical for each area. Free amino acids in the needles were analyzed as 9-fluorenylmethyl formate derivatives by high-performance liquid chromatography. The total nitrogen was determined with a CHN elemental analyzer, and other mineral nutrients were determined with an inductively coupled plasma analyzer. Arginine, glutamic acid, glutamine, γ-aminobutyric acid, and aspartic acid were the quantitatively dominating amino acids in the needles of both species from all sites in both northern and southern Sweden. These amino acids represented 50–80% of the total concentration of free amino acids in the needles. The concentration of arginine in the needles of both spruce and pine increased with decreasing site index and showed high variations between individual trees. For both species, the highest concentrations of arginine were found in the southern area, which had the highest deposition of nitrogen. Concentrations of glutamic acid, glutamine, and γ-aminobutyric acid in the needles of both species showed significant differences between some of the sites on both areas, but these differences showed no general pattern that correlated with the site indexes. In relation to nitrogen, low concentrations of phosphorus and potassium were found in needles from the poorest spruce sites in both areas compared with corresponding values for the good spruce sites. The results are discussed in relation to nitrogen deposition and mineral nutrient imbalance.

scholarly journals Measurement of the rates of protein synthesis in rabbits. A method for the estimation of rates of change in the specific radioactivities of free amino acids during continuous infusions

1980 ◽  
Vol 192 (2) ◽  
pp. 623-629 ◽  
Author(s):  
G E Lobley ◽  
S P Robins ◽  
R M Palmer ◽  
I McDonald
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rate Constants ◽  
Free Amino Acids ◽  
Free Amino ◽  
Muscle Protein ◽  
Specific Radioactivity ◽  
Free Proline ◽  
Rates Of Change ◽  
New Zealand White Rabbits

1. A method is described by which, from analysis of terminal samples, the rate constants that define the changes in specific radioactivity of free amino acids during continuous infusions can be estimated. The method involves the infusion of 3H-labelled and 14C-labelled forms of an amino acid for different, but overlapping, periods. 2. The procedure was developed for infusions of proline and tyrosine into New Zealand White rabbits and the rate constants were determined for blood and muscle. 3. The rate constant for equilibrium of radioactive free proline was much lower in muscle than in blood, and indicated that a plateau condition may not be attained in muscle by the end of a 6 h infusion. 4. Comparison of the ratio of areas under the curves of estimated specific radioactivity plotted versus time with the 3H/14C ratio of bound amino acid in muscle protein suggested that radioactive proline and tyrosine may be incorporated preferentially from an extracellular rather than an intracellular source.

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

1972 ◽  
Vol 43 (6) ◽  
pp. 823-837 ◽  
Author(s):  
D. Burston ◽  
Jill M. Addison ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Tissue Uptake ◽  
Acidic Amino Acids ◽  
Hydrolysis Of

1. The characteristics of transport and hydrolysis of twenty-two dipeptides containing basic and acidic amino acids by rat ileal rings were investigated in vitro. The peptides included combinations of basic and neutral, basic and basic, basic and acidic, acidic and acidic, and acidic and neutral amino acids. 2. All peptides studied were removed intact from the bulk phase of the incubation medium, though, in general, only free amino acids appeared in the tissue. Uptake of one or both constituent amino acids was greater from the peptide than from the equivalent amino acid or amino acid mixture in the case of at least one peptide from each group and in eighteen of the twenty-two peptides studied. In general, there was no relationship between the extent of uptake of amino acids from peptides and the extent of their hydrolysis by the system. The results support the hypothesis that there is more than one mode of uptake of amino acids from peptides. 3. Hydrolysis of γ-glutamyl-l-glutamic acid by intact intestine or intestinal homogenate was slight, and intact peptide was taken up by the tissue. Uptake of free glutamic acid from this peptide was poor. Comparison of γ-glutamyl-l-glutamic acid with three other slowly hydrolysed dipeptides, glycyl-d-valine, sarcosylglycine and glycylsarcosine, suggested that all four were transported into the mucosal cells and hydrolysed intracellularly. The results indicate that the presence of a γ-linkage or a d-amino acid, or methylation of the free amino group as in sarcosylglycine, impair both transport and hydrolysis of peptide, but that attachment of a methyl group to the N of the peptide bond, as in glycylsarcosine, impairs hydrolysis but has no effect on peptide transport. 4. l-Aspartic acid and l-glutamic acid were extensively transaminated by the intestine, whether presented as free amino acids or in peptides. Evidence was obtained suggesting that production of alanine from aspartic acid resulted from direct transamination of aspartic acid with pyruvic acid, rather than from a sequence of two reactions involving aspartate and alanine aminotransferases. 5. The results show that more rapid uptake of amino acids from peptides than from free amino acids is not confined to peptides made up of neutral amino acids, and probably occurs with many small peptides. Uptake of lysine and the dicarboxylic amino acids, which are particularly slowly absorbed from free solution, was much greater from several dipeptides than from the free amino acids. The results suggest the importance of mucosal peptide uptake in protein absorption.

Biochemische Aspekte des Aminosäuren-Stoffwechsels bei Psoriasis vulgaris / Biochemical Aspects of Amino Acid Metabolism in Psoriasis vulgaris

1973 ◽  
Vol 28 (7-8) ◽  
pp. 449-451 ◽  
Author(s):  
G. Peter ◽  
H. Angst ◽  
U. Koch
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Psoriasis Vulgaris ◽  
Normal Subjects ◽  
Pathological Process

Free and protein-bound amino acids in serum and scales were investigated. In serum the bound amino acids of psoriatics are significantly higher with exception of Pro, Met, Tyr and Phe in contrast to normal subjects. For free amino acids the differences between normal subjects and psoriatics found in serum and scales are not significant. Results are discussed in relation to the single amino acids and the biochemical correlations are outlined which takes the pathological process as a basis.

Liver extract and its free amino acids equally stimulate gastric acid secretion

1980 ◽  
Vol 239 (6) ◽  
pp. G493-G496 ◽  
Author(s):  
E. J. Feldman ◽  
M. I. Grossman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Liver Extract ◽  
Amino Acid Mixture ◽  
Acid Mixture

Using intragastric titration in dogs with gastric fistulas, dose-response studies were carried out with liver extract and with a mixture of amino acids that matched the free amino acids found in liver extract. All solutions were adjusted to pH 7.0 and osmolality to 290 mosmol x kg-1. Doses are expressed as the sum of the concentrations of all free amino acids. At each dose studied (free amino acid concentration: 2.8, 5.6, 11, 23, and 45 mM), acid secretion in response to the free amino acid mixture was not significantly different from that of liver extract. The peak response to both liver extract and the free amino acid mixture occurred with the 23-mM dose and represented about 60% of the maximal response to histamine. The serum concentrations of gastrin after liver extract and the amino acid mixture were not significantly different. It is concluded that in dogs with gastric fistula, gastric acid secretion and release of gastrin were not significantly different in response to liver extract and to a mixture of amino acids that simulated the free amino acid content of liver extract.

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