Predominant Amino Acid Research Articles

Bis[2-(3-carboxyphenoxy)carbonylethyl]phosphinic Acid (m-BCCEP): A Novel Affinity Cross-Linking Reagent for the β-Cleft Modification of Human Hemoglobin

The design and synthesis of bis[2-(3-carboxyphenoxy)carbonylethyl]phosphinic acid (m-BCCEP, 1) as a site-directed affinity reagent for cross-linking human hemoglobin have been reported as part of our long-term goal to generate artificial blood for emergency transfusions. Molecular modeling techniques were used to design the reagent, employing crystal coordinates of human hemoglobin A(0) imported from the Protein Data Bank. It was synthesized in four steps commencing from 3-hydroxybenzoic acid. The reagent 1 was converted to its trisodium salt to allow effective cross-linking in an aqueous medium. The reagent 1, as its trisodium salt, was found to specifically cross-link stroma-free human hemoglobin A(0) in the beta-cleft under oxygenated reaction conditions at neutral pH. The SDS-PAGE analyses of the modified hemoglobin pointed to the molecular mass range of 32 kDa as anticipated. The HPLC analyses of the product suggested that the cross-link had formed between the beta(1)-beta(2) subunits. Molecular dynamics simulation studies on the reagent-HbA(0) complex suggested that the predominant amino acid residues involved in the cross-linking are N-terminus Val-1 or Lys-82 on one of the beta-subunits and Lys-144 on the other. These predictions were borne out by MALDI-TOF MS analyses data of the peptide fragments obtained from tryptic digestion of the cross-linked product. The data also suggested the presence of a minor cross-link between Val-1 and Lys-82 on the opposing subunits. The oxygen equilibrium measurements of the m-BCCEP-modified hemoglobin product at 37 degrees C showed oxygen affinity (P(50) = 25.8 Torr) comparable to that of the natural whole blood (P(50) = 27.0 Torr) and significantly lower than that of stroma-free hemoglobin (P(50) = 14.19 Torr) assayed under identical conditions. The measured Hill coefficient value of 1.91 of the m-BCCEP-modified Hb product points to the reasonable retainment of oxygen-binding cooperativity after the cross-link formation.

Seasonal Variation in Nutrient Composition of Mytilus coruscus from China

Seasonal variation in the nutrient composition of Mytilus coruscus (thick shell mussel), cultivated in Shengsi Islands, Zhejiang Province, China, was investigated in this study. Proximate composition, mineral and amino acid concentrations, as well as the compositions of the lipid and fatty acid of thick shell mussels were analyzed. Proximate composition and mineral contents were seasonally varied significantly except for calcium (Ca) and lead (Pb). Glycine was the predominant amino acid in mussels throughout all seasons, while lysine, threonine, phenylalanine, and arginine were the main essential amino acids. The predominant lipids were phospholipids, followed by triacylglycerols and sterol esters. Polyunsaturated fatty acids (PUFA) predominated over saturated and monounsaturated fatty acids throughout the year. Docosahexaenoic acid (12.44-18.34% of total fatty acids) and eicosapentaenoic acid (10.79-14.60%) were the most abundant PUFA. Significant seasonal variations were observed in the compositions of most amino acids, lipid classes, and fatty acids. Cultivated Chinese thick shell mussels represent a source of the health benefiting long chain n-3 PUFA, essential amino acids, and minerals for human consumption.

Nutritional composition of breadnut seeds (Artocarpus camansi).

This work was carried out to determine the nutritional composition of breadnut (Artocarpus camansi) seeds. Matured breadnut seeds were obtained opened and the seeds were removed for analysis. They were analyzed for proximate mineral, amino acids, fatty acids and organic acids composition. The results showed the values of the proximate composition of the breadnut seeds as: protein (4.87%), fat (3.48%) and carbohydrate (26.11%). Ash and crude fiber were 3.43 and 1.20% respectively. The highest mineral content value was in phosphorus 363 mg/kg followed by potassium 325 mg/kg and sodium 248 mg/kg while the lowest value was in iron 0.05 mg/kg and copper 0.12 mg/kg. The predominant essential amino acids determined in the seeds were leucine 392 mg/kg, phenylalamine 312 mg/kg, arginine 293 mg/kg, isoleucine 245 mg/kg and lysine 275 mg/kg. The oil was rich in palmitic 21.4%, oleic 12.4 % and linolenic acid 14.8%. Lactic and citric acids were the predominant organic acid while malic, acetic and butyric acids were present in trace amount. The breadnut seeds could be used as composite flour and the oil could be a good source of edible oil for human consumption. Key words: Breadnut, nutritional composition, proximate, mineral, amino acid, fatty acids.

Optimization of Enzymatic Hydrolysis of Visceral Waste Proteins of Yellowfin Tuna (Thunnus albacares)

Fish protein hydrolysate was produced from the viscera of yellowfin tuna (Thunnus albacares). Hydrolysis conditions (enzyme activity, temperature, and time) were optimized using response surface methodology. A factorial design was applied to minimize enzyme utilization and modeling of degree of hydrolysis (r2 = 0.94). Lack-of-fit test revealed a non-significant value for the model, indicating that the regression equation was adequate for predicting the degree of hydrolysis under any combination of the variables (P < 0.05). The optimum conditions to reach the highest degree of hydrolysis were: 60.4 °C, 90.25 min, and a protease (Alcalase 2.4 L) activity of 70.22 AU/kg protein. The spray-dried tuna visceral protein hydrolysates had relatively high protein (72.34%) and low lipid (1.43%) content. The chemical score of the hydrolysate indicated that it fulfils adult human nutritional requirements except for methionine. Lysine and methionine were the first and the second limiting amino acids in that order. Phenylalanine was the predominant amino acid in the hydrolysates with respect to common carp requirement. In addition, the protein efficiency ratio of tuna visceral hydrolysate was 2.85–5.35.

Compositional and physicochemical characteristics of acid solubilized collagen extracted from the skin of unicorn leatherjacket (Aluterus monoceros)

Abstract Acid solubilized collagen (ASC) was extracted from the skin of unicorn leatherjacket ( Aluterus monoceros ) using 0.5 M acetic acid, followed by precipitation with 2.6 M NaCl. ASC with the yield of 4.19% (wet weight basis) was identified as type I collagen, which was composed of two α 1 chains and one α 2 chain. Different peptide maps were observed between ASC hydrolyzed by V8 protease and lysyl endopeptidase. The maps were also different from those of type I collagen from calf skin, suggesting the differences in amino acid sequences between both collagens. Glycine was the most predominant amino acid. ASC contained the relatively higher content of alanine, but lower contents of proline and hydroxyproline, compared with calf skin collagen. FTIR analysis showed that ASC was in triple helix structure. T max of ASC dispersed in 0.05 M acetic acid and deionized water were 27.7 and 35.8 °C, respectively. Relative viscosity of 0.03% (w/v) ASC dissolved in 0.1 M acetic acid decreased continuously as the temperature increased from 4 to 52 °C, indicating thermal destabilization or denaturation of ASC molecules. ASC had the solubility greater than 90% in very acidic pH range (pH 1–4) and the solubility decreased continuously with increasing NaCl concentrations (0–6%). Net charge of ASC and calf skin collagen became zero at pHs of 5.58 and 5.68, respectively as determined by zeta potential titration. Therefore, skin of unicorn leatherjacket can be used as an alternative collagenous source.

Clinical resistance to vicriviroc through adaptive V3 loop mutations in HIV-1 subtype D gp120 that alter interactions with the N-terminus and ECL2 of CCR5

The HIV-1 CCR5 co-receptor is a member of the chemokine receptor family of G-protein coupled receptors; for which a number of small molecule antagonists, such as vicriviroc (VCV), have been developed to inhibit HIV-1 R5-tropic replication. In this study, we analyzed an HIV-1 subtype D envelope gene from a clinical trial subject who developed complete resistance to VCV. The HIV-1 resistant envelope has six predominant amino acid changes in the V3 loop, together with one change in the C4 domain of gp120, which are fully responsible for the resistance phenotype. V3 loop mutations Q315E and R321G are essential for resistance to VCV, whereas E328K and G429R in C4 contribute significantly to the infectivity of the resistant variant. Collectively, these amino acid changes influenced the interaction of gp120 with both the N-terminus and ECL2 region of CCR5.

Partial Purification of Antioxidative Peptides from Gelatin Hydrolysates of Alaska Pollock Surimi Refiner Discharge

This study is conducted to partially purify an antioxidative peptide in a two-step gelatin hydrolysate from Alaska pollock surimi refiner discharge, which was obtained by sequential treatment with Pronase E and Flavourzyme. The two-step gelatin hydrolysate was fractionated using chromatographic methods. Based on the same protein concentration of each fraction, the antioxidative activities (85.1-95.4%) of positive fractions fractionated by ion-exchange chromatography were higher than those (27.2-87.8%) from gel filtration. Then, further purification of the positive fractions was performed. Among them, the partially purified A1C1L2G1 and A1C1L2G2 fractions showed 96.2% and 85.1% inhibition, respectively, of linoleic acid peroxidation. The A1C1L2G1 fraction was composed of 15 kinds of amino acids and the predominant amino acids were proline, glycine and alanine. The results obtained in this study suggested that the fraction partially purified through chromatographic methods from the two-step gelatin hydrolysate of Alaska pollock surimi refiner discharge could be useful as a supplementary source for improving health functionality.

Genetic changes associated with glycopeptide resistance in Staphylococcus aureus: predominance of amino acid substitutions in YvqF/VraSR

To further understand the mechanism of intermediate-level glycopeptide resistance, resulting from multiple endogenous mutations, in both laboratory-derived and clinically isolated Staphylococcus aureus. Laboratory-derived S. aureus strains were generated under selection using a variety of cell-wall-active antibiotics. Complete sequences of 27 genes, including 17 two-component histidine kinase sensors, were then compared with those of their susceptible parent strain. Further genetic analysis was performed on 125 clinical S. aureus isolates and 42 geographically diverse isolates of vancomycin-intermediate S. aureus (VISA). Selective pressure using imipenem resulted in single point mutations leading to amino acid substitutions in two genes: vraS, encoding a two-component histidine kinase sensor; and SA1702 (also called yvqF, located immediately upstream of vraS), encoding a conserved hypothetical protein. The accumulation of the mutation in two distinct proteins-MsrR, a peptide methionine sulphoxide reductase regulator, and TcaA, a teicoplanin-resistance-associated protein-correlated with further increases in the glycopeptide MIC. The prevalence of YvqF/VraSR mutants among 125 clinical isolates along with the corresponding teicoplanin MICs was as follows: 0% (0/39), < or =1 mg/L; 48.6% (17/35), 2 mg/L; 72.7% (24/33), 4 mg/L; 93.8% (15/16), 8 mg/L; and 100% (2/2), 16 mg/L. Genetic analysis of 42 VISA isolates also identified the predominant amino acid substitutions in YvqF/VraS: 9 isolates (21.4%) revealed mutations in YvqF, followed by 7 isolates with mutations in VraS (16.7%). Our findings provide novel insights into the high prevalence and genetic diversity of YvqF/VraSR mutants among clinical S. aureus isolates with reduced susceptibility to teicoplanin.

Microbial and chemical properties of aji-no-susu, a traditional fermented fish with rice product in the Noto Peninsula, Japan

Aji-no-susu is a Japanese fermented fish product prepared from salted horse mackerel Trachurus japonicus, and cooked rice. We studied the organic acid and free amino acid contents and microflora in 12 aji-no-susu products to clarify their features as a lactic-acid-fermented food. Salinity of the samples was approximately 7.0% (rice portion) and 6.0% (fish portion) (w/w). Water activity was approximately 0.9, and pH was approximately 4.4 and lower. In the rice portions, lactic acid content was very high (57 mg/g sample). The predominant amino acids were alanine (2.3 mg/g rice portion) and lysine (2.1 mg/g). In the case of long-fermented (4 and 12 months) aji-no-susu, a high content of gamma-aminobutyric acid (GABA, 1.5 and 1.4 mg/g) was detected. Total viable counts in rice and fish portions were 7.7 and 7.4 log colony-forming units (cfu)/g, respectively. The number of lactobacilli in the rice and fish portions was 7.3 and 7.1 log cfu/g, respectively. Yeasts were detected in eight samples. Furthermore, acid-tolerant lactic acid bacteria (LAB) (Lactobacillus plantarum), GABA-producing LAB (Lactobacillus sp.), and halophilic or halo-tolerant yeast (Debaryomyces hansenii) were isolated and identified. Results in this study indicate that aji-no-susu is a typical traditional lactic-acid-fermented fish product.

Characterization of unique heavy chain fibroin filaments spun underwater by the caddisfly Stenopsyche marmorata (Trichoptera; Stenopsychidae)

The silks of both Lepidoptera and its sister order Trichoptera contain a homologue of heavy chain (H-fibroin), which is assumed to determine the physical properties of the fiber, such as elasticity and toughness. The long repetitive region of the H-fibroin caddisfly Stenopsyche marmorata shows a conspicuous hierarchical structure that is composed of huge units, which are mainly constructed from four large blocks (SA, SB, SC and SD) arranged in an orderly fashion. Each block contains short, distinct motifs such as SXSXSX(SX), GPXG(X)(1-3) or triplet GGX, which also occur in lepidopteran and spider filaments. The SA, SB and SC blocks have nearly fixed amino acid numbers, while the length of the SD block varies, usually due to a variable number of GPXGXXX repeats. The multiple sandwich structure that occurs in the SB block is assumed to be unique to the caddisfly and may be related to the use of silk in an aqueous environment. The overall average of hydrophilicity in the repetitive H-fibroin region of S. marmorata is -0.609, whereas hydrophobicity prevails in most lepidopteran H-fibroins. Gly (29.51%), Pro (11.28%) and Ser (10.90%) are the three predominant amino acids of H-fibroin, and the high content of essential amino acids reflects the energy-rich food resources of the caddisfly. The H-fibroin of S. marmorata is about 400-500 kDa and expressed in both the middle and posterior silk glands, which is different from the expression pattern in Lepidoptera species.

Nitrogen metabolism in the developing ear of maize (Zea mays): analysis of two lines contrasting in their mode of nitrogen management

*The main steps of nitrogen (N) metabolism were characterized in the developing ear of the two maize (Zea mays) lines F2 and Io, which were previously used to investigate the genetic basis of nitrogen use efficiency (NUE) in relation to yield. *During the grain-filling period, we monitored changes in metabolite content, enzyme activities and steady-state levels of transcripts for marker genes of amino acid synthesis and interconversion in the cob and the kernels. *Under low N fertilization conditions, line Io accumulated glutamine, asparagine and alanine preferentially in the developing kernels, whereas in line F2, glutamine and proline were the predominant amino acids. Quantification of the mRNA-encoding enzymes involved in asparagine, alanine and proline biosynthesis confirmed that the differences observed between the two lines at the physiological level are likely to be attributable to enhanced expression of the cognate genes. *Integrative analysis of physiological and gene expression data indicated that the developing ear of line Io had higher N use and transport capacities than line F2. Thus, in maize there is genetic and environmental control of N metabolism not only in vegetative source organs but also in reproductive sink organs.

Zusammensetzung der Proteine des Humanspermas bei Oligozoo-, Teratozoo-, Asthenozoo- und Azoospermie

The amino acid analysis of seminalplasma and spermatozoa shows for the different andrological diagnoses that the predominant amino acids were aspartic--and glutamic acid, serine, glycine and lysine. Analytical data indicate that there were differences between plasma and spermatozoa for a lot of amino acids. No differences in the protein composition of the ejaculates were found between the various groups of andrological diagnoses.

Verteilung der Aminosäuren im Humansperma unter diagnostischen Gesichtspunkten*

The amino acid analysis of human semen shows for the different clinical diagnoses the predominant amino acids aspartic acid, serine, glycine, leucine and lysine. Analytical data indicate that there were differences in the amino acid composition between oligo- or azoospermia and terato- or asthenozoospermia by aspartic acid, glutamic acid, threonine, glycine, alanine and isoleucine.

In vivo genetic mutations define predominant functions of the human T-cell leukemia/lymphoma virus p12I protein

AbstractThe human T-cell leukemia/lymphoma virus type 1 (HTLV-1) ORF-I encodes a 99–amino acid hydrophobic membrane protein, p12I, that affects receptors in different cellular compartments. We report here that proteolytic cleavage dictates different cellular localization and functions of p12I. The removal of a noncanonical endoplasmic reticulum (ER) retention/retrieval signal within the amino terminus of p12I is necessary for trafficking to the Golgi apparatus and generation of a completely cleaved 8-kDa protein. The 8-kDa protein in turn traffics to the cell surface, is recruited to the immunologic synapse following T-cell receptor (TCR) ligation, and down-regulates TCR proximal signaling. The uncleaved 12-kDa form of p12I resides in the ER and interacts with the β and γc chains of the interleukin-2 receptor (IL-2R), the heavy chain of the major histocompatibility complex (MHC) class I, as well as calreticulin and calnexin. Genetic analysis of ORF-I from ex vivo samples of HTLV-1–infected patients reveals predominant amino acid substitutions within ORF-I that affect proteolytic cleavage, suggesting that ER-associated functions of p12I may contribute to the survival and proliferation of the infected T cells in the host.

Neuronal Expression of Splice Variants of “Glial” Glutamate Transporters in Brains Afflicted by Alzheimer’s Disease: Unmasking an Intrinsic Neuronal Property

Anomalies in glutamate homeostasis may contribute to the pathological processes involved in Alzheimer's disease (AD). Glutamate released from neurons or glial cells is normally rapidly cleared by glutamate transporters, most of which are expressed at the protein level by glial cells. However, in some patho-physiological situations, expression of glutamate transporters that are normally considered to be glial types, appears to be evoked in populations of distressed neurons. This study analysed the expression of exon-skipping forms of the three predominant excitatory amino acid (glutamate) transporters (EAATs1-3) in brains afflicted with AD. We demonstrate by immunocytochemistry in temporal cortex, the expression of these proteins particularly in limited subsets of neurons, some of which appeared to be dys-morphic. Whilst the neuronal expression of the "glial" glutamate transporters EAAT1 and EAAT2 is frequently considered to represent the abnormal and ectopic expression of such transporters, we suggest this may be a misinterpretation, since neurons such as cortical pyramidal cells normally express abundant mRNA for these EAATs (but little if any EAAT protein expression). We hypothesize instead that distressed neurons in the AD brain can turn on the translation of pre-existent mRNA pools, or suppress the degradation of alternately spliced glutamate transporter protein, leading to the "unmasking" of, rather than evoked expression of "glial" glutamate transporters in stressed neurons.

Combined therapy of interferon plus ribavirin promotes multiple adaptive solutions in hepatitis C virus

Hepatitis C virus (HCV) presents several regions involved potentially in evading antiviral treatment and host immune system. Two regions, known as PKR-BD and V3 domains, have been proposed to be involved in resistance to interferon. Additionally, hypervariable regions in the envelope E2 glycoprotein are also good candidates to participate in evasion from the immune system. In this study, we have used a cohort of 22 non-responder patients to combined therapy (interferon alpha-2a plus ribavirin) for which samples obtained just before initiation of therapy and after 6 or/and 12 months of treatment were available. A range of 25-100 clones per patient, genome region and time sample were obtained. The predominant amino acid sequences for each time sample and patient were determined. Next, the sequences of the PKR-BD and V3 domains and the hypervariable regions from different time samples were compared for each patient. The highest levels of variability were detected at the three hypervariable regions of the E2 protein and, to a lower extent, at the V3 domain of the NS5A protein. However, no clear patterns of adaptation to the host immune system or to antiviral treatment were detected. In summary, although high levels of variability are correlated to viral adaptive response, antiviral treatment does not seem to promote convergent adaptive changes. Consequently, other regions must be involved in evasion strategies likely based on a combination of multiple mechanisms, in which pools of changes along the HCV genome could confer viruses the ability to overcome strong selective pressures.

Changes in free amino acids and biogenic amines of Egyptian salted-fermented fish (Feseekh) during ripening and storage

Abstract The aim of this study was to investigate changes in the formation of amino acids and biogenic amines in Egyptian salted-fermented fish (Feseekh) during ripening (20 days) and storage (40–60 days). The total concentration of free amino acids increased from 8 (dry weight; DW) to 72 g/kg (DW) after 60 days of storage. The predominant free amino acids were leucine, glutamic acid, lysine, alanine, valine, aspartic acid, isoleucine and citrulline. Their concentrations accounted for 68% of the total concentration of amino acids after 60 days. The total contents of biogenic amines ranged from 84 to 1633 mg/kg (DW) during the investigated period. Cadaverine was the major amine detected in Feseekh at all sampling stages and its concentration varied between 21 and 997 mg/kg (DW). The histamine content (211 mg/kg DW) only exceeded the maximum tolerance level (200 mg/kg) after 60 days. It could be concluded that Feseekh can be consumed without any health risks between 20 and 40 days but it can be hazardous after 60 days due to the biogenic amine content.

In Vivo Genetic Mutations Define Predominant Functions of the Human T-Cell Leukemia/Lymphoma Virus p12I Protein.

The human T-cell leukemia/lymphoma virus Type 1 (HTLV-1) ORF-I encodes, a ninety-nine amino acid hydrophobic membrane protein, p12I that affects receptors in different cellular compartments. We report here that proteolytic cleavage dictates different cellular localization and functions of p12I. The removal of a non-canonical endoplasmic reticulum (ER) retention/retrieval signal within the amino terminus of p12I is necessary for trafficking to the Golgi apparatus and generation of a completely cleaved 8 kDa protein. The 8 kDa protein in turn traffics to the cell surface, is recruited to the immunological synapse following T-cell receptor (TCR) ligation and down-regulates TCR proximal signaling. The uncleaved 12 kDa form of p12I resides in the ER and interacts with the β and γc chains of the interleukin-2 receptor (IL-2R), the heavy chain of the major histocompatibility complex (MHC) class I, as well as calreticulin and calnexin. Genetic analysis of ORF-I from ex vivo samples of HTLV-1-infected patients reveals predominant amino acid substitutions within ORF-I that inhibits proteolytic cleavage, suggesting that ER associated functions of p12I may contribute to the survival and proliferation of the infected T-cells in the host.

Nutritional value OF Bottle Gourd (&lt;i&gt;Lagenaria siceraria&lt;/i&gt;) Seeds

Whole seeds, dehulled seeds and seed coats of bottle gourd seed (Lagenaria siceraria) were analysed for their proximate, amino acids and mineral compositions. The results of the analysis showed that, whole seed has highest content of moisture (17.5 &#61617; 0.21%) and ash (5.80 &#61617; 0.83%) while dehulled had highest amount of crude protein (35.0 &#61617; 0.48%) and crude lipid (39.22 &#61617; 1.48%) and seed coat contain highest amount of crude fiber (59.05 &#61617; 0.98%). The study showed a profile of seventeen amino acids (isoleucine, leucine, lysine, methionine, cysteine, phenylalanine, tyrosine, threonine, valine, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, proline and serine) with glutamic acid, leucine and aspartic acid being the predominant amino acid. The percentages (%) of essential and non-essential amino acids in dehulled seeds, whole seeds and seed coats were 44 vs 56, 41 vs 59 and 51 vs 49 respectively. The dehulled seeds contained essential amino acids that were found to be higher than WHO/FAO/UNU requirement. In whole seeds, threonine, lysine and lysine were found to be the most limiting amino acids. Seed coats were deficient in all the essential amino acids except for valine. Generally, the mineral composition of the seed was found to be relatively high, indicating the seed to be a good source of dietary elements, except for Ca, Zn, Co and Cr where very low values were obtained. Finally, the results of the study indicate that, bottle gourd seed is a potential source of protein, lipid, micro and macronutrients, and if properly utilised, could contribute in solving the problem of malnutrition and also serve as raw material for agro-based industries Keywords: Bottle gourd seeds, seed coat, proximate analysis, minerals and Amino acid composition.Global Journal of Pure and Applied Sciences Vol. 14 (3) 2008: pp. 301-306

Provision of carbon skeletons for amide synthesis in non-nodulated soybean and pea roots in response to the source of nitrogen supply

Soluble amino acids in roots and primary amino acids, which were involved in primary ammonium assimilation, in the metabolites of 14C-glucose fed to roots for 3 h in the dark were analyzed in the roots of non-nodulated soybean and pea plants grown in ammonium, nitrate or nitrogen-free media for 1 day. Compared with the effect of nitrate, ammonium supply strongly affected the content and synthesis of the amino acids in the roots. In both soybean and pea roots, the supply of ammonium increased considerably the concentrations of the primary amino acids, and asparagine was the most predominant amide, followed by glutamine. In nitrate-supplied soybean roots, the concentrations of asparagine, aspartate and alanine increased, but the concentration of glutamine was low. In the roots of pea plants grown in nitrate media, asparagine was the predominant amino acid, although the composition of the primary amino acids was little affected by nitrate supply. The proportion of amino acids synthesized from 14C-glucose increased and asparagine rather than glutamine was predominantly synthesized in ammonium-supplied soybean and pea roots, whereas in nitrate-supplied roots asparagine was more actively synthesized than glutamine, although asparagine was not predominant. The ratio of C4 (asparagine + aspartate) to C5 (glutamine + glutamate) amino acids was twofold higher in ammonium-supplied and nitrate-supplied soybean roots than in roots receiving no nitrogen. In contrast, in pea roots, the C4/C5 ratio was twofold higher only in ammonium nutrition. The results obtained suggest that the roots of leguminous plants might possess an indigenous ability to provide a carbon skeleton for preferential synthesis of asparagine rather than glutamine with a high intensity of ammonium supply.