scholarly journals Ox liver glutamate dehydrogenase. The use of chemical modification to study the relationship between catalytic sites for different amino acid substrates and the question of kinetic non-equivalence of the subunits

1984 ◽  
Vol 222 (3) ◽  
pp. 621-626 ◽  
Author(s):  
S E H Syed ◽  
P C Engel
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Modification ◽  
Glutamate Dehydrogenase ◽  
Activity Ratio ◽  
Regulatory Site ◽  
Constant Ratio ◽  
Active Centre ◽  
Catalytic Sites ◽  
The Relationship

The effect of pyridoxal 5′-phosphate on the activity of ox liver glutamate dehydrogenase towards different amino acid substrates was investigated. Both alanine and glutamate activities decreased steadily in the presence of pyridoxal 5′-phosphate. The alanine/glutamate activity ratio increased as a function of inactivation by pyridoxal 5′-phosphate, indicating that glutamate activity is lost more rapidly than alanine activity. A mixture of NADH, GTP and 2-oxoglutarate completely protected the alanine and glutamate activities against inactivation by pyridoxal 5′-phosphate. The activity of glutamate dehydrogenase towards glutamate and leucine decreased steadily in a constant ratio in the presence of pyridoxal 5′-phosphate. The effect of leucine on the alanine and glutamate activities as a function of inactivation by pyridoxal 5′-phosphate was studied. The results are interpreted to suggest that the subunits of glutamate dehydrogenase hexamer are kinetically non-equivalent with regard to activity towards the two monocarboxylic amino acids as well as glutamate, and that all three substrates share the same active centre. However, leucine is also able to bind at a separate regulatory site.

scholarly journals The Relationship between the Structure and Properties of Amino Acid Ionic Liquids

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3252 ◽  
Author(s):  
Paula Ossowicz ◽  
Joanna Klebeko ◽  
Barbara Roman ◽  
Ewa Janus ◽  
Zbigniew Rozwadowski
Keyword(s):  
Amino Acids ◽  
Ionic Liquids ◽  
Amino Acid ◽  
Surface Activity ◽  
Spectroscopic Properties ◽  
Specific Rotation ◽  
Structure And Properties ◽  
Rotation Surface ◽  
Cation Type ◽  
The Relationship

Ionic liquids based on different l-amino acids (glycine, l-valine, l-leucine, l-isoleucine, l-histidine, l-methionine, l-tyrosine, l-tryptophan, l-arginine, and l-threonine) and different cations (tetrabutylammonium (TBA), tributylmethylammonium (tBMA), didecyldimethylammonium (DDA), (2-hydroxyethyl)trimethylammonium (choline) (Chol), alkyl(C12-C14) dimethylbenzylammonium (benzalkonium) (BA), dodecyltrimethylammonium (DDTMA), hexadecyltrimethylammonium (HDTMA), octadecyltrimethylammonium (ODTMA) and 1-ethyl-3-methylimidazolium (EMIM)) have been synthesized and characterized by NMR and FTIR. Viscosity, specific rotation, surface activity, thermal stability (TG), and phase transformations (DSC) have been determined and compared with available data. Furthermore, benzalkonium, didecyldimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, and octadecyltrimethylammonium amino acid ionic liquids have been shown to exhibit surface activity. The dissolution of cellulose in amino acid ionic liquids (AAILs) composed of various cations was also investigated. Cellulose was only dissolved in EMIM salts of amino acids. In particular, the influence of the cation type on selected physicochemical and spectroscopic properties were discussed. The article is a mini review on amino acid ionic liquids.

scholarly journals Expression of a Heterologous Glutamate Dehydrogenase Gene inLactococcus lactis Highly Improves the Conversion of Amino Acids to Aroma Compounds

2000 ◽  
Vol 66 (4) ◽  
pp. 1354-1359 ◽  
Author(s):  
Liesbeth Rijnen ◽  
Pascal Courtin ◽  
Jean-Claude Gripon ◽  
Mireille Yvon
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamate Dehydrogenase ◽  
Aroma Compounds ◽  
In Vitro Tests ◽  
Limiting Factor ◽  
Keto Acid ◽  
Cheese Curd ◽  
The Impact

ABSTRACT The first step of amino acid degradation in lactococci is a transamination, which requires an α-keto acid as the amino group acceptor. We have previously shown that the level of available α-keto acid in semihard cheese is the first limiting factor for conversion of amino acids to aroma compounds, since aroma formation is greatly enhanced by adding α-ketoglutarate to cheese curd. In this study we introduced a heterologous catabolic glutamate dehydrogenase (GDH) gene into Lactococcus lactis so that this organism could produce α-ketoglutarate from glutamate, which is present at high levels in cheese. Then we evaluated the impact of GDH activity on amino acid conversion in in vitro tests and in a cheese model by using radiolabeled amino acids as tracers. The GDH-producing lactococcal strain degraded amino acids without added α-ketoglutarate to the same extent that the wild-type strain degraded amino acids with added α-ketoglutarate. Interestingly, the GDH-producing lactococcal strain produced a higher proportion of carboxylic acids, which are major aroma compounds. Our results demonstrated that a GDH-producing lactococcal strain could be used instead of adding α-ketoglutarate to improve aroma development in cheese.

Glutamate Dehydrogenase from Pea Roots: Purification and Properties of the Enzyme

1971 ◽  
Vol 49 (1) ◽  
pp. 127-138 ◽  
Author(s):  
E. Pahlich ◽  
K. W. Joy
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Glutamate Dehydrogenase ◽  
Constant Ratio ◽  
Ph Optimum ◽  
Purification And Properties ◽  
Activity Ratios ◽  
Single Protein ◽  
Michaelis Constants ◽  
Pea Roots

Glutamate dehydrogenase (L-glutamate: NAD+ oxidoreductase (deaminating), EC 1.4.1.2) has been purified 1250-fold from pea roots. The preparation contains only a single protein, and the molecular weight was estimated to be 208 000 ± 10 000. The enzyme shows NADH (aminating) and NAD+ (deaminating) activities, but the ratio of these activities is not constant and can be changed experimentally. NADPH activity is also present and shows a relatively constant ratio to NAD+ activity. EDTA inhibits NADH activity in intermediate concentrations, but reactivates at higher concentrations. NAD+ (and NADPH) activity is only slightly changed by EDTA. The effects of dioxane and the coenzymes on the enzyme are also reported. Mechanisms which could explain the different activity ratios, in terms of two interconvertible enzyme forms, are discussed.The pH optimum for NADH and NAD+ activities is about pH 8.0. Michaelis constants were found to be: α-ketoglutarate, 3.3 × 10−3 M; ammonium (sulfate), 3.8 × 10−2 M; glutamate, 7.3 × 10−3 M; NADH, 8.6 × 10−4 M; NAD+, 6.5 × 10−4 M. The enzyme is highly specific for the substrates glutamate and α-ketoglutarate, showing no alanine or aspartate dehydrogenase activity, and no deamination with a range of amino acids.

THE RELATIONSHIP BETWEEN SOIL BACTERIA WITH SIMPLE NUTRITIONAL REQUIREMENTS AND THOSE REQUIRING AMINO ACIDS

1957 ◽  
Vol 3 (1) ◽  
pp. 73-80 ◽  
Author(s):  
T. M. B. Payne ◽  
J. W. Rouatt ◽  
A. G. Lochhead
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Soil Bacteria ◽  
Single Case ◽  
The Other ◽  
Nutritional Requirements ◽  
Soil Organisms ◽  
Specific Amino Acid ◽  
The Relationship ◽  
Maximum Development

Twenty-two of 30 representative soil bacteria having simple nutritional requirements, in that they showed maximum development in a medium of inorganic salts and sugar, were found to be able to synthesize a variety of amino acids, though in no single case were more than four ninhydrin-positive substances found. The culture filtrates permitted the growth of amino-acid-requiring bacteria to the extent that they contained the specific amino acid or acids required by strains of the latter group. The findings point to an associative action between these nutritional groups of soil organisms and suggest that the preferential stimulation in the rhizosphere of bacteria requiring amino acids may be ascribed in part to the ability of the other group of bacteria, which are numerically increased in the rhizosphere, to synthesize amino acids.

Amino acids in muscle and kidney of potassium-deficient rats

1960 ◽  
Vol 199 (1) ◽  
pp. 39-42 ◽  
Author(s):  
Ira K. Brandt ◽  
Victor A. Matalka ◽  
Jerome T. Combs
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Nitrogen ◽  
Potassium Deficiency ◽  
Experimental Diet ◽  
Basic Amino Acids ◽  
The Relationship ◽  
Predictable Variation

Muscle and kidney taken from rats with potassium-deficiency alkalosis contained a higher concentration of lysine, histidine and arginine than tissue taken from pair-fed control animals. The concentration of anserine, carnosine and alpha-amino nitrogen did not differ in the two groups. Although the concentration of virtually all of the above substances varied with the length of time that the animal had been receiving the experimental diet, the relationship between the data obtained from potassium-deficient animals and from the pair-fed controls remained constant. The results suggest that a mechanism other than replacement of lost potassium as cation may bring about the increase in the basic amino acids during potassium-deficiency alkalosis and that starvation is associated with a predictable variation in some of the amino acid constituents of the tissues.

Increased plasma concentrations of the 5-HT precursor amino acid tryptophan and other large neutral amino acids in violent criminals

1997 ◽  
Vol 27 (2) ◽  
pp. 477-481 ◽  
Author(s):  
T. ERIKSSON ◽  
L. LIDBERG
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Healthy Controls ◽  
Violent Behaviour ◽  
Violent Crimes ◽  
Amino Acid Tryptophan ◽  
The Relationship ◽  
The Brain ◽  
Abnormal Brain

Background. Aggression has been suggested to be related to abnormal brain 5-HT activity. This amine is synthesized in brain from tryptophan, which is transported through the blood–brain barrier in competition with other amino acids. The relationship between tryptophan and its endogenous amino acid competitors in plasma might thus influence the availability of tryptophan in the brain and consequently brain 5-HT activity.Methods. Plasma amino acids were determined in 89 offenders who had committed various violent and non-violent crimes and in 14 healthy controls.Results. Both tryptophan and its competitors were higher in offenders who had committed violent crimes compared both with non-violent offenders and with controls. No difference was, however, seen in the relationship between tryptophan and its competitors.Conclusions. The results support the contention that violent behaviour is related to biochemical deviations but could not explain a possible decreased brain 5-HT activity.

scholarly journals The relationship between placental protein synthesis and transfer of amino acids

1983 ◽  
Vol 210 (1) ◽  
pp. 99-105 ◽  
Author(s):  
M J Carroll ◽  
M Young
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Guinea Pig ◽  
Specific Radioactivity ◽  
Protein Amino Acid ◽  
Naturally Occurring ◽  
Placental Protein ◽  
The Relationship ◽  
Radioactivity Measurements

The relationship between placental protein synthesis and transfer of amino acids from mother to foetus was studied in the guinea pig, by using [U-14C]-lysine, -leucine, -glycine, -aspartate and -alpha-aminoisobutyrate. The uptake of label by protein was 12-16% of total label transferred. Cycloheximide inhibited incorporation of all naturally occurring amino acids into protein by 81-96% and transfer by 62-75%; the concentration of label in the free pool was increased for each. These findings were confirmed when specific-radioactivity measurements were made with L-[U-14C]lysine. The transfer of the non-protein amino acid alpha-aminoisobutyrate was not significantly decreased by cycloheximide. A model, linking protein synthesis to the generation of a transfer pool of amino acids, is proposed whereby inhibition of protein synthesis decreases the amount of amino acid available for transfer.

DIGESTION IN THE RUMEN AND AMINO ACID SUPPLY TO THE DUODENUM OF SHEEP FED ENSILED AND FRESH ALFALFA

1986 ◽  
Vol 66 (4) ◽  
pp. 1019-1027 ◽  
Author(s):  
D. A. FLORES ◽  
L. E. PHILLIP ◽  
D. M. VEIRA ◽  
M. IVAN
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rumen Fluid ◽  
Essential Amino Acids ◽  
Ruminal Ph ◽  
Sheep Rumen ◽  
Branched Chain ◽  
High Degree ◽  
The Relationship ◽  
Adaptation Phase

A study was conducted with six sheep equipped with rumen and duodenal re-entrant cannulae to investigate differences in duodenal amino acid supply with fresh and ensiled alfalfa. The experiment was conducted as a cross-over design with two 12-d periods consisting of an adaptation phase (5 d) followed by feces collection (5 d), and finally on day 12, 24 h continuous collection of duodenal digesta and sampling of rumen fluid. During the experiment the sheep were restricted on feed to 52 g DM d−1 kg−0.75. Analyses of the forages revealed extensive breakdown of threonine, lysine and other basic amino acids, and high degree of preservation of branched chain amino acids. Relative to the amount consumed, there was a net loss of amino acids at the duodenum with fresh alfalfa but a net gain with silage. The relationship between intake of individual essential amino acids and duodenal recovery was inconsistent. Duodenal recovery of total essential amino acids was 28% higher with fresh than with ensiled alfalfa, a difference which was most pronounced with threonine and lysine. Digestion of organic matter and fiber was unaffected (P > 0.05) by ensiling of alfalfa. Estimates of ruminal pH were higher (P < 0.05) for silage than fresh forage (6.9 vs. 6.7) but VFA concentrations were lower (P < 0.05) for silage (52.1 vs. 64.1 mmol L−1). Rumen ammonia levels were similar for the two forages. The deficit in duodenal supply of essential amino acids with silage is discussed in relation to the problem of silage intake in ruminants. Key words: Alfalfa silage, duodenal amino acids, sheep, rumen digestion

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