Qualitative Amino Acid Composition Research Articles

Hairy roots biochemical characteristics of vegetable pea’s morphotype with modified leaf

Hairy roots biochemical characteristics of vegetable pea’s morphotype with modified leaf

Характеристика и использование синтезированного антимикробного пептида в составе биоразлагаемой пищевой пленки

One direction in the development of food packaging involves the use of biodegradable safe materials along with antimicrobial agents. Among the promising prescribed ingredients for biodegradable films are biopeptides with antimicrobial properties. The research goal was to develop a biodegradable food film using a synthesized antimicrobial peptide. The objects of the study were the peptide, test strains of C. albicans, Escherichia coli, and Bacillus subtilis. The confirmation of the purity and primary structure of the peptide was conducted using mass spectrometry. The antimicrobial activity of the peptide was studied using the disc diffusion method on both Gram-positive and Gram-negative bacteria. The degree of film biodegradation was determined after 1, 3, and 6 months by exposing it to microorganisms. The peptide ACSAG was synthesized, and its quantitative and qualitative composition of amino acids, sequence, and molecular mass corresponded to a known antimicrobial peptide. It was estab­lished that the synthesized peptide possesses antimicrobial activity against E. coli ATCC 25922 and B. subtilis. A composition for the biodegradable film was developed, incorporating agar-agar, glycerin, antimicrobial peptide, and distilled water. It was demonstrated that the addition of the peptide to the film composition reduces its biodegradability.

Amino acid analysis of muscle tissue of walleye and pike of the Volgograd reservoir

The purpose of our study is to analyze the data on the amino acid composition of the muscle tissue of common walleye and common pike obtained in the natural conditions of the Volgograd reservoir and to establish their nutritional value for the human body. The data obtained indicate that the quantitative and qualitative composition of amino acids of the muscle tissue of hydrobionts is similar; there is a general high content of glutamic and aspartic acids, arginine, lysine, isoleucine and leucine. The total number of proteinogenic amino acids exceeds the muscle tissue of walleye by 15.58%. It is also noted that the composition of the muscle tissue of the pike perch includes the largest amount of essential amino acids. The content of cystine and histidine in the studied samples is the least in terms of quantity. The natural nutrition of pike and pike perch is not balanced enough in terms of the content of high-grade protein, but it is enough for the growth of fish in the conditions of the Volgograd reservoir. Under natural conditions, pike perch and pike did not receive the amino acid valine in their diets. The biological value of the protein of the muscle tissue of the common pike is 1.43% higher compared to the muscle tissue of the common pike perch.

Amino acid composition of proteins of meristem cells of maize roots under the combined action of lead, cadmium and nickel ions

Heavy metals are one of the main causes of plant damage. The main route of entry of metals into plants is their absorption by the root system from the soil. The accumulation of heavy metals in plants disrupts the flow of biochemical processes. Amino acid metabolism is one of the important factors that ensure biochemical adaptation of organisms to environmental changes. Therefore, the aim of the work was to study the content of protein amino acids in the generative tissues of the maize root under the combined action of lead, cadmium and nickel ions at the early stages of ontogenesis. To assess the impact of heavy metals, two-day-old corn seedlings were transplanted to solutions with heavy metal ions of various concentrations, both individually and in a mixture. The content of protein amino acids in the meristem was characterized by significant variation associated with both quantitative and qualitative changes in the composition of water-soluble proteins during germination. The level of accumulation of amino acids in the meristem cells of maize roots depended on the concentration of the xenobiotic and the germination period, and the general regularity of the influence of nickel ions was a decrease in the content of arginine, leucine, alanine and an increase in the content of histidine, cysteine, serine, proline, and valine. During the period of germination, the qualitative amino acid composition of plants did not change, while the quantitative content of individual amino acids varied greatly. Various increases in the content of dicarboxylic amino acids (glutamate and aspartate) testify to the intensification of metabolic processes under the influence of the studied substances. However, it cannot be excluded that the increase in the content of glutamic and aspartic acids is associated with a decrease in the speed of their utilization. In addition, heavy metals caused an increase in the content of amino acids of the ornithine cycle (arginine) and the end product of the cycle (proline) to varying degrees. Proline is an amino acid that has a stress-protective effect due to the binding of proline aggregates to surface hydrophobic residues of proteins, which prevents their denaturation. Perhaps a similar protective effect of proline occurs in the case, which is being considered.

Analysis Of The Influence Of Alcohol-Induced Stress On The Quantitative And Qualitative Composition Of Amino Acids Related To S-Adenosylmethionine And Glutathione Transformations

Studies of preparations that decrease oxidative stress and, as a consequence, that can prevent or reduce the development of alcoholic liver disease are relevant. A wide range of drugs, the bioprotective effect of which is studied, in its action is associated with natural antioxidant systems. Therefore, the study of the features of these systems is necessary for the effective development of bio protectors. The aim is to analyze changes in the quantitative and qualitative composition of amino acids involved in antioxidant mechanisms in the presence of alcohol-induced stress in rats. In the presence of alcohol-induced oxidative stress, there are changes in the quantitative and qualitative composition of amino acids (methionine, serine, taurine), which are involved in the mechanisms of antioxidant protection - cycles of S-adenosylmethionine and glutathione. A slight increase in methionine levels in the blood serum of animals of the experimental group and disruption of the recovery cycle of methionine under alcohol-induced oxidative stress are arguments for the ineffectiveness of S-adenosylmethionine as a bioprotective substance. The same decrease in the level of serine (by 15%) and taurine (by 13%), and analysis of literature data, may be indicate the "secondary" nature of glutathione as an antioxidant compared to taurine.

Growth, development, morphology and biochemical characteristics of <i>Solidago canadensis</i> L. plants when introduced in the middle taiga subzone of the Komi Republic

The paper presents the results of a long-term study of four samples of Canadian goldenrod (Solidago canadensis L.) of different geographic origin introduced in the middle taiga subzone of the Komi Republic. Under cultural conditions, the species is highly resistant and longevity (up to 18 years). It has been established that with the introduction in the North, reproduction of the Canadian goldenrod is possible by vegetative means, as well as from seeds of foreign origin. The mass transition of plants grown by seedlings to the generative period occurs in the third year of life. According to the flowering rhythm (July 31 September 25), the species is classified as a mid-summer-mid-autumn plant. Fruiting of plants is interrupted by frost, full-fledged seeds are not formed. The morphological features of the generative shoot have been studied. The plant height in culture reaches 143155 cm. The number of leaves on the stem is 63101. The floral part of the shoot (inflorescence) 3039 cm long is formed from the axils of 4149 leaves and consists of 2141 paracladia 813 cm long. The number of baskets on one shoot in different specimens of Canadian goldenrod varies from 2700 to 4200. The content of nitrogen mass fraction (1,83,0%) in the aboveground raw phytomass of Canadian goldenrod has been studied for the first time and the quantitative and qualitative composition of amino acids in plant proteins has been determined. The total content of amino acids in the plant raw material of Canadian goldenrod has varied from 7,9 to 15,1% over the years. In the aboveground phytomass of plants, 17 amino acids have been found and determined, including 7 irreplaceable ones. The share of essential amino acids has averaged 37% of the total. The highest rates of equity participation have been noted for the following amino acids: proline, glutamic, aspartic, lysine, leucine, valine, alanine, arginine and glycine 13,2; 11,0; 10,8; 8,4; 8,0; 5,9; 5,8; 5,7 and 5,2%, respectively. In the conditions of the North, biochemical studies of this species have been carried out for the first time. The content of flavonols in the aboveground raw phytomass of Canadian goldenrod have been 4,55,7% and met the requirements for medicinal raw materials (more than 3%). The yield of essential oil and its component composition have been determined. The EO content in the aboveground phytomass of plants has varied from 0,85 to 1,7% in terms of absolutely dry raw material. In the composition of EM, 39 components have been reliably identified, nine of which have been attributed to the main ones. The dominant compounds are: -pinene (up to 43,9%), myrcene (up to 18,2%), limonene (up to 13,2%), -3-carene (up to 12,0%); from sesquiterpenoids: germacrene D (up to 54,3%), bornyl acetate (up to 5,8%), geranyl acetate (up to 2,4%), cadinadiene (up to 2,0%), sesqui-fellandrene (up to 1,4%).

INFLUENCE OF NODULE BACTERIA STRAINS OF SINORHIZOBIUM MELILOTI ON THE AMINO ACID CONTENT IN THE TOPS OF ALFALFA UNDER DIFFERENT WATER SUPPLY

Objective. To study the amino acid composition in the tops of alfalfa under different water supply (60 % MVC (maximum water capacity) and 30 % MVC) depending on the inoculum strain (Sinorhizobium meliloti 425a, T17, AC08). Methods. Microbiological (bacterial cultivation), physiological (vegetation experiment), biochemical (determination of amino acid content in the tops of plants). Results. It was established that the qualitative amino acid composition in the tops of ALFALFA was identical in all variants. However, quantitative content of the studied samples differed depending on the inoculum strain and water supply. It was found that aspartic and glutamic acids, leucine and lysine are dominant in the tops of alfalfa under different water supply. In the absence of moisture, an increase in the content of individual amino acids was reported at the background of Sinorhizobium meliloti AC08 and T17, while inoculation with Sinorhizobium meliloti 425a resulted in a decrease in the content of all amino acids except tyrosine. In plants exposed to water stress, a tendency towards decrease in the content of glutamic acid at the background of bacterization with Sinorhizobium meliloti 425a and increase — under inoculation with Sinorhizobium meliloti T17 and AC08 was reported, which may support the use of the latter to increase the ability of symbiotic systems to recover during a post-stress period. Conclusion. Pre-sowing inoculation of alfalfa of the variety Laska with new active strains of Sinorhizobium meliloti AC08 and T17 helps to increase the content of amino acids, in particular essential, in the tops of plants, both under optimal conditions of moisture and insufficient water supply. The prospects of using new strains of rhizobia in the cultivation of alfalfa for green mass under the conditions of optimal water supply and drought has been verified.

Comparative Analysis of Minerals, Heavy Metals and Amino Acids Compositions of the Seeds and Juice of Cucumis metuliferus

The aim of this study was to compare the minerals, heavy metals and amino acids compositions of the seeds and juice of Cucumis metuliferus. The minerals and heavy metals content were evaluated using FS240AA agilent atomic absorption spectrometer according to the method of American Public Health Association while the amino acids content was evaluated using High Performance Liquid Chromatography (HPLC). From the mineral analysis, concentrations of calcium (23.416 ppm), aluminum (0.094 ppm), manganese (0.242 ppm) and iron (1.243 ppm) were higher in the juice than in the seeds with respective values of 20.084 ppm, 0.079 ppm, 0.221 ppm and 0.934 ppm while the concentrations of magnesium (29.749 ppm), zinc (4.184 ppm), copper (0.125 ppm), sodium (8.927 ppm) and potassium (7.594 ppm) were higher in the seeds than in the juice with respective values of 20.592 ppm, 1.271 ppm, 0.030 ppm, 8.594 ppm and 6.833 ppm. The juice had higher concentrations of heavy metals such as arsenic (20.082 ppm), lead (4.135 ppm), cobalt (0.178 ppm), silver (0.074 ppm), selenium (7.246 ppm) and mercury (4.609 ppm) as against the seed with respective values of 0.578 ppm, 1.455 ppm while cobalt, silver, selenium and mercury were not detected. However, the concentrations of cadmium (0.389 ppm), chromium (0.545 ppm) and nickel (0.288 ppm) were higher in the seeds than in the juice with respective values of 0.082 ppm, 0.252 ppm and 0.016 ppm. From the result of amino acid analysis, 18 amino acids were found in both the seeds and juice which include 9 essential and 9 non-essential amino acids respectively. The qualitative composition of amino acids in both the seeds and the juice was same, but the quantitative contents differed although non-significantly from each other with prevalence of amino acids in the seeds. Aspartate was the most abundant of the amino acids found while cysteine was the least. These results suggest that the seeds and juice of Cucumis metuliferus contain adequate essential minerals which are beneficial to human health. The contaminant levels of heavy metals highlights the necessity on the quality and safety concerns about their use and handling. The amino acids analysis showed that both the seeds and juice of Cucumis metuliferus are good sources of amino acid and could be used as food supplement. The amino acid content may also provide useful information for determination of the protein quality of Cucumis metuliferus.

СВОБОДНЫЕ И СВЯЗАННЫЕ АМИНОКИСЛОТЫ В ПОЧВАХ ЛЕСОСТЕПИ ПОВОЛЖЬЯ И ИХ РОЛЬ

The article presents the results of studying the amino acid composition in the prevailing soils of the region (RT): sod-podzolic, gray forest, brown-gray, leached chernozem. Free and related amino acids are identified, their quantitative indicators are given. A study of the qualitative composition of free amino acids in the soils of the region showed that they are close in the qualitative composition of amino acids, but differ in their quantitative content. The total content of free amino acids is 4-20 mg/kg and increases in the series of soils: sod-medium podzolic, brown-gray, gray forest and leached chernozem. Moreover, there are significant differences in the content of individual groups of free amino acids: in all soils, most of the free amino acids are represented by neutral and basic amino acids (65-80%), much smaller by dicarboxylic (11-29%) and cyclic (5-11%). Easily and hardly hydrolyzable fractions of organic nitrogen are the closest reserves of nitrogen available to plants. Identification of the amino acid composition of these nitrogen fractions showed that the qualitative composition of bound amino acids is almost the same as free. In the studied soils, 19-31% of nitrogen of easily hydrolyzable and 33-60% of nitrogen of hard hydrolyzable fractions are represented by amino acid nitrogen. At the same time, 40-54% of the total amount of nitrogen of amino acids falls on the share of neutral, and 14-28% - on the share of basic amino acids. Their content naturally increases from sod-podzolic to gray soil and to chernozem, both in the composition of easily hydrolyzed and difficultly hydrolyzed fractions, which indicates an improvement in the quality of nitrogen in this direction.

Amino acid composition in determination of collagen origin and assessment of physical factors effects

The amino acid composition of collagen is a characteristic feature of this protein. Collagen, irrespective of its origin, contains 19 amino acids, including hydroxyproline which does not occur in other proteins. Its atypical amino acid composition is characterized by high content of proline and glycine, as well as the absence of cysteine.This paper shows the comparison of qualitative composition of amino acids of fish skin (FS) collagen, bovine Achilles tendon (BAT) collagen, and bone collagen. Results demonstrate that FS collagen as well as BAT collagen contains no cysteine and significantly different amount of hydroxyproline. In BAT collagen hydroxyproline content is 30% higher than hydroxyproline content of FS collagen. In bone collagen the amount of hydroxyproline is two times more than in FS collagen.Furthermore, it is shown that sensitivity to radiation of individual amino acids varies and depends on the absorbed dose of ionizing radiation. The changes observed in the amino acid composition become very intense for the doses of 500kGy and 1000kGy.

The Effect of Copper And Zinc Nanoparticles on the Growth Parameters, Contents of Ascorbic Acid, and Qualitative Composition of Amino Acids and Acylcarnitines in Pistia stratiotes L. (Araceae).

The paper covers the research of copper and zinc nanoparticle effect on the content of ascorbic acid, and quantitative and qualitative composition of amino acids and acylcarnitines in Pistia stratiotes L. plants. Plant exposition to copper nanoparticles led to the decrease in (1) the amount of ascorbic acid, (2) the total content of amino acids (by 25 %), and (3) the amount of all studied amino acids except for the glycine amino acid. At this, the amount of 5-oxoproline, arginine, leucine, ornithine, phenylalanine, proline, serine, and tyrosine was two times lower than in control plants. The reduction of the contents of 8 out of 12 investigated acylcarnitines (namely C0, C2, C3, C5, C6, C8, C16, C18:1) was observed in plants under the influence of copper nanoparticles. The result of plants incubation with zinc nanoparticles was the decrease in (1) the amount of ascorbic acid, (2) the total content of amino acids (by 15 %), (3) the content of leucine, methionine, phenylalanine, proline, and tyrosine (more than twice), and (4) the content of 10 acylcarnitines (C0, C2, C3, C4, C5, C10, C16, C18, C18:1, C18:2). The observed reduction in amino acid contents may negatively affect plants adaptive reactions associated with de novo synthesis of stress proteins. At the same time, the decrease in the content of acylcarnitines, responsible for fatty acid transportation, may lead to the changes in the activity and direction of lipid metabolism in plants and reduce plant’s ability to use free fatty acids as the oxidation substrate for cell reparation.

Preliminary research on amino acid composition and nutritional value of clover proteins

The amino acid composition and nutritional value of 5 clover varieties including 3 Polish ones ('Gloria', 'Hruszowska', 'Skrzeszowicka') and 2 of foreign origin ('Rotra' and 'Violetta') were investigated. No significant differences in the total protein content (19.2–20.0% of dry matter) as well as in qualitative amino acid composition were found among the clover varieties under examination. EAA index (Essential amino acid index) calculated according to Oser for 'Gloria' and 'Hruszowska' showed the highest nutritional value was – 40. The lowest value of EAA index was found for 'Violetta' cvar. – 32, intermediate values however for Rotra and Skrzeszowicka was 37 and 36.

Effect of root exudates of various plants on composition of bacteria and fungi communities with special regard to pathogenic soil-borne fungi

The purpose of the studies conducted in the years 1996 - 1998 was to determine the composition of bacteria and fungi populations in the rhizosphere of winter wheat, spring wheat, soybean and potato, and in non-rhizosphere soil. Besides, the effect of root exudates of these plants on the formation of pathogenic fungi communities was established. The microbiological analysis showed that the greatest tolal number of bacteria was found in the rhizospheres of potato and soybean, and the lowest number in non-rhizosphere soil. The smallest total number of fungi was found in the rhizosphere of winter wheat, and the largest in the rhizosphere of soybean. Pathogenic fungi dominated in the rhizospheres of soybean and potato, while non-rhizosphere soil was the poorest in these microorganisms. Among the pathogenic fungi, <i>Fusarium oxysporum, F.culmorum</i> and <i>F.solani</i> were most frequently isolated. Soybean roots exudated the greatest amount of aminoacids, and acidic aminoacids, which have a positive effect on the development of phytopathogens, dominated in their content. On the other hand, the best quantitative and qualitative composition of aminoacids was found out in the root exudates of winter wheat, since they conlained big amounts of alkaline and aromatic aminoacids.

Amino acids and trace elements from Callisia fragrans

Callisia fragrans Wood. (Commelinoceae) is a cultivated plant, the fresh leaves and runners of which are used as raw material for producing juice that possesses, judging from experimental results, pronounced adaptogenic and motor-protective activity and contains harmless compounds [1]. The contents of neutral, glycoand phospholipids and their fatty acids, ascorbic acid, organic acids, chlorophyll, and carotinoids in various plant organs have been reported [2]. The phenolic composition of the plant has been studied [3]. Our goal was to determine the amino-acid and mineral composition of C. fragrans juice. Raw material was grown in industrial plots of the Russian Research Institute of Medicinal and Aromatic Plants (VILAR, Moscow). Fresh runners (100 g) were ground in a blender. The resulting pulp was filtered through cotton tissue to produce juice (86 mL) of density 1.005 g/cm3. The resulting juice (20 mL) was placed in a Soxhlet apparatus and purified of lipophilic substances using CHCl3 (100 mL) for 2 h on a water bath. The purified juice was treated with lithium-citrate buffer (pH 2.2). Proteins were precipitated by sulfosalicylic acid solution (0.1 mL, 30%). Samples were centrifuged and analyzed for amino acids on an AAA 339 analyzer (Czech Rep.). The qualitative composition of amino acids was determined by retention time using a standard mixture consisting of 24 amino acids as references. The quantitative content of amino acids was calculated in μg/mL of juice using peak areas as the parameter. Table 1 lists the results. Bound amino acids were determined after acid hydrolysis by HCl solution (6 N) at 110°C for 24 h. We found 15 free amino acids including 6 essential ones. A total of 14 bound amino acids was observed, of which 7 were essential. The mineral composition was determined on a DFS-8 spectrograph with a planar diffraction grating using spectral emission analysis. Runners of C. fragrans contained 11 elements (Table 2). The plant accumulates moderate levels of Ba, Mn, and Cu [4].

Peptide conjugates of benzene and toluene metabolites in English ryegrass

Biotransformation of [1-6-14C]benzene and [1-14C]toluene in English ryegrass (Lolium perenne L.) seedlings was investigated. Vapors of these compounds were absorbed by the leaves of this plant. Benzene and toluene were oxidized, forming phenol and benzoic acid, respectively. A portion of phenol and benzoic acid was bound by low-molecular-weight peptides forming conjugates. A qualitative amino acid composition of the peptides involved in the conjugation was determined. After removing plants from the atmosphere containing [1-6-14C]benzene and [1-14C]toluene, the radioactivity of the conjugates gradually decreased. This process was accompanied by the evolution of 14CO2, indicating the breakdown of these conjugates. Radioactive compounds thus formed were oxidized, yielding carbon dioxide. A portion of phenol and benzoic acid, along with peptide conjugation, was subjected to further oxidative transformations up to disruption of the aromatic ring. By this pathway, nonvolatile carboxylic acids, such as muconic, fumaric, succinic, malic, malonic, glycolic, and glyoxylic, were formed. Using electron microscopy, a damaging effect of benzene on the cell ultrastructure of English ryegrass leaves was shown, and this toxic effect depended on the benzene concentration.

Changes in the amino acid pool during embryonic development of cultured and wild Atlantic salmon ( Salmo salar)

Changes in amino acid content (free and protein-bound) of cultured and wild (anadromous) Atlantic salmon eggs and alevins were compared during development. Eggs collected from wild Atlantic salmon had higher amounts of free and protein-bound amino acids due to their larger size than those collected from cultured stock. The qualitative composition of amino acids ( nmol mg ) in egg tissues from cultured and wild stocks did not differ. Total amino acid pool of eggs and alevins declined during development, but an increase in the free amino acid pool was noted through development. At the same temperature, the development of embryos and alevins of the wild stock was faster than that of the cultured stock. Protein-bound amino acids, alanine, arginine, aspartic acid, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine and valine were decreased in both cultured and wild salmon, suggesting their importance in embryonic and alevin development.

Yield, Nitrogen-fixing Capacity, and Main Cellular Constituents of some Azotobacters, Isolated from Egyptian Soils and Waters

Summary The yield, the efficiency of dinitrogen fixation, and the main cellular constituents, namely proteins, carbohydrates, and lipids of some azotobacters, grown in N-deficient liquid medium under shaking and static culture conditions were investigated. The bacterial growth, as well as the nitrogen content was found to be greatly affected by the species and strains specificity as well as by the culturing conditions employed. Among the various isolated organisms, Azotobacter chroococcum (strain 12) exhibited the highest values of cell mass yield (5.5 g dry wt. organisms/l), total nitrogen fixed (324 ppm), and efficiency of N2-fixation (54 mg N fixed/g C oxidized) after 7 d under shaking culture conditions. All strains showed an increase in the yield efficiency ratio (YER) in case of aerated cultures, compared to static ones. On the other hand, the efficiency of nitrogen fixation (ENF) correlated inversely with the available oxygen of the substrate. There were considerable variations in the crude protein efficiency ratio (CPER), total carbohydrates efficiency ratio (TCER), and total lipids efficiency ratio (TLER) among the different species and strains under either condition of cultivation. Static cultures gave higher main cellular constituents and caloric values than shaking ones. The protein was found to be the major constituent of organic matter of the Azotobaoter cells. The qualitative amino acid composition of azotobacters is a stable characteristic of the culture when grown under fixed conditions. The chromatographic analysis of the protein hydrolyzate of Azotobacter cells revealed the presence of twenty amino acids. Moreover, the Azotobacter protein is not lacking in any of the nutritionally essential amino acids.

Many hitherto unknown peptides are principal constituents of uremic "middle molecules".

The aim of the present investigation was to collect information on the molecular composition of uremic "middle molecules," the 500-5000 molecular-mass serum constituents assumed to be involved in the molecular etiology of uremic intoxication. For this purpose, three fractions of serum containing such molecules were separated by cation-exchange column chromatography. These fractions absorb at 240 nm and are characteristically increased in chronic uremia. By one-dimensional paper chromatography of these fractions it was demonstrated that each could be resolved into at least seven (altogether, 21) ninhydrin-positive subfractions. These, like the original fractions, yielded amino acids on acid hydrolysis. The qualitative amino acid composition of the subfractions differed substantially, both from each other and from that of 31 known peptides with which they were compared. We conclude that hitherto unknown peptides with only limited diffusibility through hemodialysis membranes constitute the main bulk of uremic middle molecules.

Extraction of tracheal sap from Citrus and analysis of its nitrogenous compounds

AbstractTracheal sap was extracted from sections of stems (0.5 to 1.5 cm in diameter and 7.5 to 15.0 cm in length) of orange trees (Citrus sinensis (L.) Osbeck cv. Washington Navel) by using a combination of the vacuum and liquid displacement methods. The volume of sap obtained and its concentration of nitrogenous compounds were dependent on the volume of displacing liquid used for the extraction. Four ml of water‐saturated 1‐butanol extracted essentially all of the xylem fluid present in the stem sections without apparent production of artifacts.The time of sampling affected the nitrogen concentration of the tracheal sap, but not the content of xylem nitrogen per volume of stem material. The orientation of the stems in the tree and the diameter of the stems had an effect on their contents of xylem nitrogen, with southeastern orientation and thinner stems showing higher concentrations.We could not detect the presence of ammonium, nitrites or proteins in the tracheal sap of orange trees. Most of the nitrogen was present as amino acids and about 2% of the total in the form of nitrates. The qualitative composition of amino acids, as determined by TLC, was the same both in winter and spring tracheal sap. The main components of the sap were proline and arginine in winter, and these amino acids together with asparagine and aspartic acid in spring.

Amino acid analysis of synalbumin

Synalbumin-positive (insulin antagonistic) and synalbumin-negative (insulin non-antagonistic) albumins were analysed for their amino acid composition by two dimensional descending paper chromatography. The analysis did not reveal any differences in the qualitative amino acid composition of these albumins.