Effect of trophic conditions on asparagine transamination in wheat plants

In dialyzed extracts from winter wheat plants transamination reactions occurred between asparagine and α-ketoglutaric acid (L-asparagine+2-oxoacid=2-oxosuccinamate+ +amino acid; 2. 6. 1. 14). Reactions with pyruvate exhibited a very low activity. Besides transamination products,i. e. glutamate and alanine, aspartic acid was formed in both reactions. Deamidation was more intensive in the weak reaction asparagine-alanine and less intensive in the asparagine-glutamate reaction. When calculated per dry weight unit the activity was the same in plants of all variants (three experimental variants—Knop, potassium humate, water). A higher, activity was found in root dialysates; however, a highly significant difference could be observed only between shoots and roots of Knop variant. When evaluating results in terms of protein content we found a significant difference between mineral variant (Knop—the lowest activity) and both deficient variants (potassium humate, water—the highest activity). Thus the highest growth activity was in connection with the lowest transamination activity and vice versa, which was the same as in transaminations of aspartic acid. In the case of asparagine, too, one can consider the possibility of its utilization via transamination for biosynthesis of glutamic acid in plants which have, for reasons of nutrition, a low level of this metabolically important amino acid.     

Effect of trophic conditions and humic acid on alanine transamination in wheat plants

In dialyzed extracts from winter wheat plants an intensive enzymatical transamination reaction occurred between L-α-alanine and α-ketoglutaric acid (L-α-alanine + + 2-oxoglutarate = pyruvate + L-glutamate, EC 2.6.1.2) as well as a weak nonenzymatical transamination reaction, practically immeasurable. Pyridoxal-5’-phosphate strongly affected the reaction rate. Besides the transamination product-glutamate, γ-aminobutyric acid was formed in this reaction. This amino acid could have originated neither via proteolysis of the enzyme extract, nor via decarboxylation from glutamate formed, nor via transamination of succinic-γ-semialdehyde after α-ketoglutarate decarboxylation. This was the only case of its formation in the transamination reactions investigated in our laboratory — it originated from the alanine-glutamate reaction only, and the mechanism of its biosynthesis cannot be elucidated for the present. Dialysates from shoots exhibited a significantly higher enzymatic activity in comparison with those from roots. The effect of trophic conditions (Knop’s nutrient solution, a water solution of potassium humate, water) was not revealed when calculating per dry weight unit. However, when calculating per protein unit an increased activity was found in the dialysates from shoots of both nutrient — deficient variants. Roots of plants cultivated in potassium humate had the lowest activity. The discussion concerns the possibility of an adaptive use of this transamination for increasing the essential glutamate level in green parts of the plants cultivated under unfavourable nutritive conditions, and also deals with a further characteristic of the differing metabolism of plants cultivated in humate.     

The effect of humic acid on transamination in winter wheat plants

A very low, for the most part unmeasurable glutamic-aspartio transminase activity and a very high glutamic-alanine transaminase activity was found in the overground parts and roots of young wheat plants. The roots had a higher glutamic-alanine transaminase activity than the overground parts in the first and second leaf stage. Plants cultivated in Knop’s nutrient solution (variant with humate and without) showed a higher glutamic-alanine transaminase activity than poorly growing plants, cultivated in distilled water (with humate and without). In plants cultivated in nutrient solutions, transaminase activity increased with the age of the wheat plants. As in the previous experiments, the effect of humate was only significant, in the roots of plants cultivated in distilled water with humate, where transamination activity was greater than in the control without humate. The roots of this variant with a stimulatory growth effect showed a large accumulation of free sugars in the previous experiments. The connection between these effects of humate on the roots of young winter wheat plants is discussed.     

The effect of humus substances on the level of free amino acids in wheat plants

The presence of potassium humate (commercial sample of Humussäure Riedel-de Haën A. G., Seelze-Hannover) in distilled water led to an increase in the content of alanine, aspartic and glutamic acid in the overground parts of wheat plants as compared with the content of these substances in control plants grown in distilled water. In plants cultivated on nutrient solutions a higher level of alanine and glutamic acid and a considerably lower level of amides was found than in plants grown in distilled water and in water with humate. Generally the content of amino acids was higher in the overground parts than in the roots after a cultivation period of one week as well as of 14 day. In the overground parts of 1 days old plants the level of aspartic acid, asparagine and alanine was found to be higher and that of glutamine lower than in seven days old plants. In the roots of the examined plants a decrease of the amino acid content accurred almost in all cases after a cultivation period of 14 days as compared to one of 7 days.     

Catabolism of amino acids in bacteria of the genus Klebsiella

Propagation and activity level of 18 enzymes catalyzing deamination reactions of dicarboxylic and oxyamino acids and enzymes of amino acid reamination and amino acid N-acyl-derivatives' deacylation have been studied in Klebsiella bacteria. Klebsiella the most actively utilizes serin, threonine, aspartic and glutamic acids and aromatic amino acids. The first three amino acids are utilized by deamination, aromatic acids- in aminotransferase reaction with alpha-ketoglutaric acid, glutamic acid--by deamination and decarboxylation. Besides, Klebsiella actively deacylates N-acyl-derivatives of amino acids.     

Correlation between [U-14C]glucose metabolism and function in perfused cat brain

In brain perfusion experiments conducted with blood containing [U-14C]glucose the relative specific activity (RSA) of blood glucose carbon incorporated in brain intermediate metabolites was measured. It was demonstrated that the so-called metabolic pattern of Geiger is not constant, but it bears a close relation to the function of the brain. The results of the study may be summarized briefly as follows. (1) In a group (A) of cats with a high level of brain function, the RSA of lactic acid was 75 per cent; that of glutamic acid 80 per cent; aspartic acid 75 per cent; glutamine 61 per cent; GABA 43 per cent; and respiratory CO2 55 per cent. It was observed that the major part of the carbon of amino acids, such as glutamic acid and aspartic acid, which are directly associated with the tricarboxylic acid cycle are derived from blood glucose. (2) In a group (B) showing a low level of brain function, the RSA of each amino acid was considerably lowered. The RSA of glutamic acid and aspartic acid was about 50 per cent and that of respiratory CO2 was 27 per cent. (3) In a group (C) with a still lower level of brain function, each amino acid as well as the respiratory CO2 had still lower RSA values. (4) The metabolic pattern of Geiger corresponds to values obtained during low functional activity of the brain in our experiment.     

The Enzymatic Activity of Fungal Xylanase Is Not Necessary for Its Elicitor Activity

Fungal xylanases from Trichoderma spp. are potent elicitors of defense responses in various plants. To determine whether enzymatic activity is necessary for elicitor activity, we used site-directed mutagenesis to reduce the catalytic activity of xylanase II from Trichoderma reesei. For this, the glutamic acid residue at position 210, which is part of the active center in this family of enzymes, was changed to either aspartic acid (E210D) or serine (E210S). Wild-type and mutated forms of xylanase II were expressed in yeast cells and purified to homogeneity. Compared with the wild-type form of xylanase II, E210D had >100-fold and E210S 1,000-fold lower enzymatic activity. In contrast, these mutated forms showed no comparable drop in elicitor activity. They fully stimulated medium alkalinization and ethylene biosynthesis in suspension-cultured tomato (Lycopersicon esculentum) cells, as well as hypersensitive necrosis in leaves of tomato and tobacco (Nicotiana tabacum) plants. These results provide direct evidence that enzyme activity is not necessary for elicitor activity of fungal xylanase.     

Tracer studies on the biosynthesis of amino acids from lactate by Peptostreptococcus elsdenii

Peptostreptococcus elsdenii, a strict anaerobe from the rumen, was grown on a medium containing yeast extract and [1-(14)C]- or [2-(14)C]-lactate. Radioisotope from lactate was found in all cell fractions, but mainly in the protein. The label in the protein fraction was largely confined to a few amino acids: alanine, serine, aspartic acid, glutamic acid and diaminopimelic acid. The alanine, serine, aspartic acid and glutamic acid were separated, purified and degraded to establish the distribution of (14)C from lactate within the amino acid molecules. The labelling patterns in alanine and serine suggested their formation from lactate without cleavage of the carbon chain. The pattern in aspartic acid suggested formation by condensation of a C(3) unit derived directly from lactate with a C(1) unit, probably carbon dioxide. The distribution in glutamic acid was consistent with two possible pathways of formation: (a) by the reactions of the tricarboxylic acid cycle leading from oxaloacetate to 2-oxoglutarate, followed by transamination; (b) by a pathway involving the reaction sequence 2 acetyl-CoA-->crotonyl-CoA-->glutaconate-->glutamate.     

三叶木通果实生物学特性及营养成分的研究

本文报道了陕西省野生三叶木通果实的生物学特性及营养成分。三叶木通座果率低。落果高峰在5月下旬,以短缩枝结果为主;果实纵横径生长呈双S曲线,食用部分是发达胎座;果实类型有紫红皮和黄褐皮,或随圆形和卵圆形。成熟果实富含矿物质,可溶性糖主要是果糖,有机酸主要是乳酸,蛋白质氨基酸主要是谷氨酸、天门冬氨酸、赖氨酸和亮氨酸。脂肪酸主要是油酸和亚油酸。种子脂肪酸主要是油酸。果实可食率低。     

Mechanism of Proline Production by Kurthia catenaforma

The fate of aspartic acid used for proline fermentation by Kurthia catenaforma was traced by using aspartic acid-U-(14)C. The radioactivities of proline and glutamic acid increased with the disappearance of aspartic acid. After 40 hr, aspartic acid disappeared from the medium and radioactive alpha-ketoglutaric acid was detected. The radioactivity of proline reached 44% of aspartic acid radioactivity at 40 hr. The specific radioactivities of these amino acids and of alpha-ketoglutaric acid supported the notion that proline is produced mainly from aspartic acid via alpha-ketoglutaric acid and glutamic acid. Since the levels of glutamic acid dehydrogenases (EC 1.4.1.2 and EC 1.4.1.4) were low in this organism, it appears that the nitrogen atom of aspartic acid enters proline by the action of aspartate aminotransferase (EC 2.6.1.1). The mechanism of proline production is discussed on the basis of the role of aspartic acid in this fermentation.     

The effect of copper and nitrogen on the amino acid composition of oat straw

Summary The effect of fertilization with nitrogen and copper on the amino acid composition of oat straw has been studied.The plants (Avena sativa cv Yielder) were grown in peat with a very low copper content and supplied with two levels of nitrogen (NH₄ or NO₃) and three levels of copper sulphate.The higher level of nitrogen stimulated growth only when copper was added, whereas, without copper, it had an adverse effect on growth and prevented grain formation altogether. The higher level of nitrogen increased the nitrogen content of the straw at all levels of copper, but particularly in plants receiving no copper.Total amino acids in the straw hydrolysate of copper sufficient oats accounted for about 50% of the total N and was about 20% higher in copper-deficient tissues. The addition of copper caused a decrease in the amounts of all amino acids. The relative proportions of most of the amino acids to glycine remained fairly constant. Threonine, serine, alanine, iso-leucine, histidine and arginine showed small significant differences with copper treatment, whereas valine, tyrosine, phenylalanine, proline, lysine and cysteic acid (derived from cysteine and cystine) showed no differences. The proportion of aspartic acid relative to glycine in the straw hydrolysate was greatly increased in copper deficient plants supplied with the higher level of nitrogen, particularly as ammonium. The proportion of glutamic acid was also increased by the higher level of nitrogen, but showed no effect of added copper. Most of the difference in aspartic acid could be accounted for as free asparagine. The possible reasons for higher proportions of asparagine are discussed in relation to the metabolism of the oat plant.     

Effect of L-Aspartic Acid and L-Glutamic Acid on Production of L-Proline

To elucidate the effect of aspartic acid on growth of Kurthia catenaforma during the proline fermentation, this organism was compared with other bacteria with respect to the rate of consumption of aspartic acid, and to the activities of enzymes concerned in the metabolism of aspartic acid. Although no marked difference in enzyme activities was observed, the aspartic acid consumption rate of K. catenaforma was markedly higher than that of other organisms. The consumption of glutamic acid by K. catenaforma was not detected at 24 hr of culture. The difference between the consumption of aspartic acid and glutamic acid in this strain might result from a difference in permeability to the amino acids. We considered that L-glutamic acid might substitute for L-aspartic acid if the uptake of glutamic acid could be increased. A number of detergents were screened for their effect on consumption of glutamic acid. Cetyltrimethylammonium bromide, sodium laurylphosphate, and polyoxyethylene sorbitan monolaurate were found to increase the transport rate of glutamic acid, but not of aspartic acid. A method of producing L-proline from glutamic acid was established with the aid of detergents.     

Influence of carbon and nitrogen sources on growth, nitrogenase activity, and carbon metabolism of Gluconacetobacter diazotrophicus

The effects of different carbon and nitrogen sources on the growth, nitrogenase activity, and carbon metabolism of Gluconacetobacter diazotrophicus were investigated. The amino acids asparagine, aspartic acid, and glutamic acid affected microbial growth and nitrogenase activity. Several enzymatic activities involved in the tricarboxylic acid cycle were affected by the carbon source used. In addition, glucose and gluconate significantly increased the oxygen consumption (respiration rate) of whole cells of G. diazotrophicus grown under aerobic conditions. Enzymes responsible for direct oxidation of glucose and gluconate were especially active in cells grown with sucrose and gluconate. The presence of amino acids in the apoplastic and symplastic sap of sugarcane stems suggests that these compounds might be of importance in the regulation of growth and nitrogenase activity during the symbiotic association. The information obtained from the plant-bacterium association together with the results of other biochemical studies could contribute to the development of biotechnological applications of G. diazotrophicus.     

EFFECTS OF DIETARY PROTEINS ON FETAL BRAIN PROTEIN AND GLUTAMIC ACID METABOLISM IN RAT

Abstract— The effects of feeding dietary wheat and Bengal gram proteins to pregnant rats on brain protein and glutamic acid metabolism in 15-, 17- and 19-day fetuses were investigated. Wheat and Bengal gram diets resulted in loss of brain weight with decreased DNA, RNA, protein, free x amino N and deficits in the activities of brain glutamine synthetase, glutaminase I. glutaminase II and glutamate decarboxylase at all the gestational ages studied without any change in glutamine transferase activity. The concentrations of the amino acids alanine, glutamic acid, glutamine and GABA were found to be significantly lower on wheat and Bengal gram diets than the control on a 10% casein diet. The wheat with lysine and Bengal gram with methionine, cystine and tryptophan resulted in similar mean values of all the characteristics studied to the mean values observed in rats on the control diet. However, glutaminase I activity remained significantly low on lysine fortified wheat diet, and aspartic acid content was found to increase on both fortified and unfortified wheat and Bengal gram diets. A 20% casein diet showed increased brain weight, DNA. RNA. protein and free x amino N concentrations as compared with the 10% casein diet, while the other parameters remained unchanged.     

Effect of coordinated addition of specific amino acids on the synthesis of recombinant glucose isomerase

The amplified expression of a recombinant protein is known to lead to an intracellular depletion of specific amino acid pools which in turn may affect the production of the desired protein. In order to counteract and overcome such a situation during the fermentation of the recombinant Escherichia coli (PMSG27) containing the glucose isomerase (GI) gene from Streptomyces sp. NCIM 2730, the effect of addition of different amino acids on the specific activity of GI was studied. The amino acid composition of GI from Streptomyces sp. NCIM 2730 reveals predominantly aspartic acid, glutamic acid, and glycine; therefore, in the present paper, the effect of coordinated addition of the assorted combinations of these three amino acids on the synthesis of recombinant GI was studied. The results were analyzed using a 2³ factorial design. The following conclusions were derived from the analysis of two-factor interactions of the three amino acids: (i) The interaction between the aspartic and glutamic acid is independent of aspartic acid concentration but is affected by the increasing concentrations of glutamic acid, (ii) The effect of aspartic acid concentration is more than that of glycine, and (iii) During the interaction of glutamic acid and glycine, the effect of glutamic acid is more prominent than that of glycine. The three-factor interaction analyses reveal that the effect of the three amino acids is in the order aspartic acid > glutamic acid > glycine.     

Free and protein amino acids,and nutrient concentrations in wheat grain as affected by phosphorus nutrition at various salinity levels

Summary The effects of P nutrition under various salinity levels on the protein, amino acids, and nutrients in mature wheat grain were studied. Mexican dwarf wheat (Triticum aestivum L. var Inia) was grown to maturity in solution cultures with variable concentrations of P (0.5-, 5-, 25- and 50 mg P/l) in combination with NaCl at concentrations producing osmotic potentials (_s) of –0.4-, –1.4-, –2.4- and –4.4-bars. All other essential nutrients were present in adequate concentrations for vigorous plant growth.Increasing levels of P in the nutrient solutions tended to decrease the grain yield, N, Cl, protein-glutamic acid,-proline,-leucine,-glycine, and-serine, while P, K, Mg, Zn, Mn and Cu in the grain were increased. The sum of all protein amino acids in the grain decreased as the concentration of P increased in the nutrient solution. The effect of P on the individual and sum of amino acids tended to show peak amounts at the 5.0 mg P/l treatment level.Increased levels of salinity significantly reduced grain yield, N, proteinglutamic acid,-proline,-leucine,-glycine,-serine,-aspartic acid,-alanine, and-phenylalanine in the grain. The sum of the protein amino acids (mol/g dry wt.) was decreased in the grain from plants grown at –4.4 bars salinity level, but not in the grain from plants receiving less saline treatments. The concentrations of free amino acids: serine, aspartic acid, glutamic acid, alanine, and arginine were lower in the grain produced at the –4.4 bars salinity than at –0.4 bars salinity level. The sum of free amino acids (mol/g dry wt.) in the grain were decreased at the highest salinity level as compared with concentrations found for grain produced at lower salinity levels.There were some interactions found between P and salinity on the protein amino acids and nutrients in the grains.The amounts of essential amino acids expressed in mg/g of protein were not significantly affected by the increasing levels of P and salinity in the nutrient solution and they were found in adequate or greater amounts than those recommended by the World Health Organization and FAO.     

The activity of glutamic acid decarboxylase from intact wheat roots

Experiments with isolated wheat roots and with intact wheat plants showed that glutamic acid decarboxylase from the roots takes part in the transformation of substance in the medium and that its activity is influenced by the medium. Glutamic acid decarboxylase is thus a factor taking part in the formation of substances excreted by the plants roots.     

Phytoprotective Effect of Ammonium Humate at High Copper Concentrations in the Environment

The influence of ammonium humate obtained from peat on the tolerance of wheat plants to high CuSO₄ concentrations (100, 250, 500, and 1000 μM/L) has been studied. Seeds were germinated on a copper sulfate solution with and without the humate. Then the plants were grown on Hoagland’s solution in an artificial climate chamber. The coefficient of protective action by humate was estimated in the following two ways: by dry weight changes and by the copper ion content in comparison with the plants grown without humate. The protective role of the humate at 100 and 250 μM has been established, which is due to reduction of copper accumulation in the plants. It has been found that the humate at higher concentrations enhances the toxic effect of copper.     

Seasonal changes in the free amino acids of oat and barley phloem sap in relation to plant growth stage and growth of Rhopalosiphum padi

The concentrations and composition of free amino acids in phloem sap from two cultivars of oats and barley, both susceptible to the aphid Rhopalosiphum padi, were determined by means of high performance liquid chromatography. Sap was collected from excised aphid stylets at three developmental stages (seedlings, tillering plants and plants undergoing stem elongation) from plants given or not given fertiliser and grown outdoors. In connection, the growth of individual R. padi nymphs was estimated at the same phenological stages on plants grown in the greenhouse. The content of free amino acids was consistently higher in seedlings than in plants at the early tillering stage. Only in seedlings did the addition of fertiliser increase amino acid levels. Barley phloem sap contained more free amino acids than that of oats when fertiliser was added and at later developmental stages. Phloem sap of oats and barley showed similar patterns in their composition of free amino acids at the seedling stage, but as the plants grew older the patterns became increasingly different. Plants given fertiliser had higher amounts of dicarboxylic amino acids (glutamic and aspartic acid) than unfertilised plants. The concentrations of γ-amino butyric acid, glycine, histidine, and methionine were very low in all treatments. The relative growth rates of R. padi nymphs were low when amino acid content was low and vice versa. The results are discussed in relation to host plant suitability and plant resistance mechanisms.     

Physiology of growth and sporulation in Bacillus cereus. I. Effect of glutamic and other amino acids

Buono, F. (Syracuse University, Syracuse, N.Y.), R. Testa, and D. G. Lundgren. Physiology of growth and sporulation in Bacillus cereus. I. Effect of glutamic and other amino acids. J. Bacteriol. 91:2291-2299. 1966.-Growth and sporulation were studied in Bacillus cereus by use of an active culture technique and a synthetic medium. A high level of glutamic acid (70 mm) was required for optimal growth and glucose oxidation followed by sporulation even though relatively little glutamic acid was consumed (14 mm). Optimal growth occurred with a combination of 14 mm glutamic acid and 56 mm (NH(4))(2)SO(4), aspartic acid, or alanine. Ornithine or arginine at 70 mm could replace glutamic acid in the synthetic medium without affecting the normal growth cycle. Glutamic acid was not replaced by any other amino acid, by (NH(4))(2)SO(4), or by a combination of either alpha-ketoglutarate or pyruvate plus (NH(4))(2)SO(4). Enzyme assays of cell-free extracts prepared from cells harvested at different times were used to study the metabolism of glutamic acid. Glutamic-oxaloacetic and glutamic-pyruvate transaminases were completely activated (or derepressed) during early stages of sporulation (period of 6 to 8 hr). Alanine dehydrogenase responded in a similar manner, but the levels of this enzyme were much higher throughout the culture cycle. Neither glutamic dehydrogenase nor alpha-ketoglutarate dehydrogenase was detected. Sporulation in a replacement salts medium was studied with cells harvested at different times from the synthetic medium. Cultures 2 to 6 hr old were unable to sporulate in the replacement salts medium unless glutamic acid (7.0 mm) was present. By the 6th hr, cells were in the early stages of sporulation, showing spore septa development. Cultures 8 hr old sporulated in the replacement salts medium. Other metabolic intermediates able to replace glutamic acid in the replacement salts medium were alanine, aspartic acid, and glutamine at equimolar concentrations. Also, ammonium ions in combination with pyruvic, oxaloacetic, alpha-ketoglutaric, or fumaric acid replaced glutamic acid. The likely role of these metabolites is discussed.