Amino acid composition of wheat grain. 1: Changes during development

The changes in the composition of free and total amino acids in wheat grain during development are described: the experiment was performed in a growth chamber with three varieties of winter wheat (Triticum aestivum L.): Splendeur, Hobbit and Maris Huntsman. The changes in the total composition of amino acids of the grain as development progressed were consistent with an increase in the proportion of storage proteins. At 15 days after anthesis, the relative amount of glycine increased, suggesting that at this moment the proportion of gliadins was relatively low. The relative amount of arginine increased in mature grain, showing that at times close to maturity the relative proportion of synthesis of a protein fraction rich in this amino acid increased. Free glutamate, proline and arginine decreased at 15 days to a greater extent than the other amino acids and was present in low relative amounts during the period of maximum protein synthesis in the grain; these three amino acids could be the most limiting for protein synthesis in grain. In the free fraction the following showed a similar pattern of change during grain development: aspartate, arginine and histidine on the one hand, and on the other alanine, valine, leucine, isoleucine, threonine, phenylalanine and tyrosine; moreover both groups were inversely correlated. Glycine and lysine were directly related to each other and inversely to glutamate.     

Supplementary effect of aestivum wheat (Triticum aestivum L), bengal gram (Cicer arietinum L) and soya bean (Glycine max L) on protein quality of durum wheat (Triticum durum Desf)

Chapatis and parathas were made from different combinations of durum (Triticum durum Desf) and aestivum (Triticum aestivum L) wheat to test for their organoleptic acceptability. The best accepted durum/aestivum (40:60) combination was supplemented at 10, 20, 30 and 40% levels with Bengal gram (Cicer arietinum L) flour and soya protein (Glycine max L) concentrate. Raw and cooked samples were analysed for some amino acids and trypsin inhibitor activity. The most acceptable cooked products were fed to growing rats for estimation of protein efficiency ratio, apparent digestibility and plasma proteins. Cooking resulted in considerable losses in cystine, available lysine and trypsin inhibitor activity. The losses were greater in paratha than in chapati. Protein efficiency ratio and apparent N digestibility of chapatis were significantly higher than those of parathas. However, protein quality of soya-supplemented parathas was better than that of chapatis.     

The phenolic acid and polysaccharide composition of cell walls of bran layers of mature wheat (Triticum aestivum L. cv. Avalon) grains

The purpose of this study was to examine the carbohydrate and phenolic‐ester composition of cell walls in wheat bran layers. Four defined layers of wheat bran were separated manually from mature grains of wheat (Triticum aestivum L. cv. Avalon) to give samples of beeswing bran (outer pericarp), cross cells, testa + nucellar epidermis and aleurone cells. The cell‐wall material from each layer, and from a sample of intact bran, was analysed for carbohydrates and wall‐bound esterified phenolic acids. The cell‐wall material of intact bran was rich in arabinose and xylose with significant quantities of glucose and uronic acid and a relatively small amount of galactose and mannose. The varying ratios of arabinose:xylose in cell walls of isolated bran layers indicated that the heteroxylans had tissue‐specific substitution patterns. HPLC analysis of phenolic acids identified significant amounts of esterified ferulic acid and 8‐8′‐ (aryltetralin form), 5‐8′‐, 5‐5′‐, 8‐0‐4′‐ and 5‐8′‐(benzofuran form)‐dehydrodiferulic acids in the isolated cell walls. Ferulic acid was highly concentrated in the aleurone layer, whereas dehydrodiferulates were concentrated in the beeswing bran and cross cells. The role of phenolic cross‐linking is discussed in relation to the architecture of the cell walls of wheat bran and to processing implications. Copyright © 2005 Society of Chemical Industry     

Pleiotropic increases in free non-polar lipid, glycolipid and phospholipid contents in waxy bread wheat (Triticum aestivum L.) grain

BACKGROUND: Diethyl ether‐extractable free lipid (FL), non‐polar or neutral lipid (NL), glycolipid (GL) and phospholipid (PL) contents and water‐saturated 1‐butanol (WSB)‐extractable non‐starch lipid (NSL)—monogalactosyldiglyceride (MGDG), digalactosyldiglyceride (DGDG) and phosphatidylcholine (PC)—contents in bread wheat (Triticum aestivum L.) grain were evaluated to elucidate the possible influence of the Wx‐D1 gene on the lipid composition. RESULTS: Waxy near‐isogenic lines with a non‐functional Wx‐D1d allele showed consistently increased NL, GL and PL contents among FL and MGDG, DGDG and PC contents among NSL compared with non‐waxy near‐isogenic lines with a functional Wx‐D1a allele throughout three growing/harvest seasons. However, the proportion of NL, GL and PL among FL was not influenced by the non‐waxy/waxy state of the endosperm. The nearly non‐functional Wx‐D1f allele influenced the FL and NL contents in a similar manner to the non‐functional allele across two seasons, while the partly functional Wx‐D1g allele only affected the NL content. CONCLUSION: The Wx‐D1 locus has pleiotropic effects on the diethyl ether‐extractable FL, NL, GL and PL contents and WSB‐extractable MGDG, DGDG and PC contents of bread wheat grain. The non‐functional Wx‐D1d allele causes an increase in the levels of these lipids. Copyright © 2012 Society of Chemical Industry     

Isolation and partial characterisation of two low molecular weight durum wheat (Triticum durum) glutenins

Two low molecular weight durum wheat (Triticum durum Desf) glutenins, DSG-1 and DSG-2 (durum-wheat sulphur-rich glutenin fractions) were isolated from two cultivars, Mondur of good technological quality and Kidur of poor technological quality. The glutenin fraction, composed mostly of DSG protein, was extracted using a low concentration of NA-tetradecanoate and then fractionted by by using molecular sieve chromatography (Bio-Gel P 30). The amino acid compositions and the N-terminal sequences of the pure DSG proteins were determined, and their hydrophobic characteristics, calculated on the basis of these data, showed that DSG-2 is more hydrophobic than DSG-1. The amino acid compositions of DSG-1 and DSG-2 were different. The N-terminal amino acids of DSG-1 and DSG-2 were also different but were identical for each of the two cultivars. In the case of DSG-1, in addition to the main chain a minor chain was found in which the first three amino acids of the main chain were missing. The minor chain represented about 30% int he DSG-1 of mondur and almost 50% in Kidur.     

Free amino acid composition in primary and secondary inflorescences of 11 broccoli (Brassica oleracea var italica) cultivars and its variation between growing seasons

Eleven broccoli cultivars were grown in the field in spring/summer (April–July) and summer/winter (September–January). Free amino acid composition was determined by HPLC in primary and secondary inflorescences separately. A total of 17 amino acids were identified: L ‐alanine (Ala), L ‐arginine (Arg), L ‐asparagine (Asn), L ‐aspartic acid (Asp), glycine (Gly), L ‐glutamic acid (Glu), L ‐glutamine (Gln), L ‐histidine (His), L ‐isoleucine (Ile), L ‐leucine (Leu), L ‐methionine (Met), L ‐phenylalanine (Phe), L ‐serine (Ser), L ‐threonine (Thr), L ‐tryptophan (Trp), L ‐tyrosine (Tyr) and L ‐valine (Val). The major amino acid was L ‐glutamine, which represented on average between 39.5% (in cvs Durango and Green Valiant) and 55.5% (in cv Shogun) of the total amino acid content among cultivars, followed by L ‐glutamic acid with a variation between 12.1% (in cv Shogun) and 17.4% (in cv Marathon). A few amino acids represented less than 1% each (Gly, Leu, Met, Phen, Thr, Trp and Tyr). For most of the amino acids there were significant differences between cultivars, whilst only a few amino acids showed significant variations between inflorescences. Season also induced significant differences in the content of most of the identified amino acids. The cultivar with the highest total free amino acid content (323.9 mmol kg⁻¹ DW) on average of both seasons (391.3 in spring/summer and 256.4 in summer/winter) was Shogun, whilst the others were above the minimum of 177.3 mmol kg⁻¹ DW found in cv SK3. There was a general tendency for higher total amino acids levels in spring/summer than in summer/winter, but it was clear that this effect was dependent on the cultivar. © 2000 Society of Chemical Industry     

酸奶中游离氨基酸含量及乳清蛋白组成分析

用反相高效液相色谱法（RP-HPLC）测定了5种原味发酵型酸奶中游离氨基酸含量，并用十二烷基硫酸钠-聚丙稀酰胺凝胶电泳（SDS-PAGE）分析了酸奶乳清蛋白组成。结果表明：被测酸奶中乳清蛋白含量的范围在5.66-10．45g／L，其主要成分为α-乳清蛋白、β-乳球蛋白及少量酪蛋白。用HPLC在酸奶中检测到17种氨基酸，总游离氨基酸质量浓度范围285．90-1116．21mg／L，其中4个品牌酸奶中精氨酸（她）质量浓度最高，1个品牌酸奶中天冬氨酸（Asp）质量浓度最高。     

Biochemical composition,protein quality and amino acid profile of red-toothed triggerfish (Odonus niger), an underutilised fish

The present study aims to assess the seasonal and sex-wise variations in proximate composition, amino acid profile and protein quality of Odonus niger, which will be the first report for this species. High-protein (15.15%–20.05%) and low-fat contents (0.46%–1.94%) were observed for the species studied. The highest protein was observed in September and December for male and female fishes respectively. The total essential amino acid (TEAA) content was 58.65–77.41 mg g⁻¹ (males) and 60.25–77.38 mg g⁻¹ (females) and leucine was the predominant EAA in both the sexes. The EAA index and biological value ranged between 17.50–22.56 and 7.38–12.89 for males and 18.02–22.48 and 7.94–12.80 for female fishes respectively. In male, TEAA followed Sept>Jan > Dec > Aug > Oct > Nov and in female it was Oct > Sept>Dec > Nov > Aug > Jan. The chemical score for histidine and threonine was more than the FAO recommended values. Overall, the nutritional quality of this unconventional species proved very good and comparable with other commercially important lean fishes.     

Interrelationships among seed yield, total protein and amino acid composition of ten quinoa (Chenopodium quinoa) cultivars from two different agroecological regions

BACKGROUND: Quinoa is a good source of protein and can be used as a nutritional ingredient in food products. This study analyses how much growing region and/or seasonal climate might affect grain yield and nutritional quality of quinoa seeds. RESULTS: Seeds of ten quinoa cultivars from the Andean highlands (Bolivia/Argentina site) and Argentinean Northwest (Encalilla site) were analysed for seed yield, protein content and amino acid composition. Grain yields of five cultivars growing at Encalilla were higher, and four were lower, compared with data from the Bolivia/Argentina site. Protein contents ranged from 91.5 to 155.3 and from 96.2 to 154.6 g kg^?1 dry mass for Encalilla and Bolivia/Argentina seeds respectively, while essential amino acid concentrations ranged from 179.9 to 357.2 and from 233.7 to 374.5 g kg^?1 protein respectively. Significant positive correlations were found between the content of essential amino acids and protein percentage. CONCLUSION: It appears that there are clear variations in seed yield, total protein content and amino acid composition among cultivars from the two sites. Essential amino acid composition was more affected than grain yield and protein level. The study revealed that both environmental and climatic factors influence the nutritional composition of quinoa cultivars growing in different agroecological regions. Copyright © 2011 Society of Chemical Industry     

Postharvest changes in ammonium,amino acids and enzymes of amino acid metabolism in asparagus spear tips

Harvested asparagus (Asparagus officinalis L) spears accumulate ammonium and amino acids in their tips during storage at ambient temperatures. To further investigate these phenomena the authors held spears at 20°C in the dark after harvest and examined several parameters of amino acid metabolism in the tips. Soluble protein content declined faster than total protein over the 5-day storage period. Protein loss was accompanied by an increase in total free amino acids with asparagine showing the most dramatic increase. A pronounced accumulation of ammonium occurred, starting after 3 days. The activities of glutamine synthetase (EC 6.3.1.2) and aspartate and alanine aminotransferases (EC 2.6.1.1 and EC 2.6.1.2, respectively) declined slightly whereas glutamate dehydrogenase (EC 1.4.1.2) activity almost doubled over 5 days. Phenylalanine ammonia lyase (EC 4.3.1.5) activity declined rapidly during the first 2 days and then partially recovered. Asparagine synthetase (EC 6.3.1.1), asparagine aminotransferase (EC 2.6.1.14), asparaginase (EC 3.5.1.1) and glutaminase (EC 3.5.1.2) activities were not detectable at any time during the storage period. Ammonium accumulation could be caused by increased glutamate dehydrogenase activity coupled with a shortage of aspartate.     

Protein,amino acid and fatty acid contents in raw and canned sea urchin (Paracentrotus lividus) harvested in Galicia (NW Spain)

Moisture, protein, amino acid and fatty acid contents of raw and canned sea urchin (Paracentrotus lividus) gonads were determined. Sea urchin showed a high moisture content (73%) and a high level of proteins (56% dry matter). The canning process, evaluated at 112 °C for 50 min, did not lead to significant changes in protein, amino acid and fatty acid contents relative to the raw sample. © 2000 Society of Chemical Industry     

Relationships between amino acid composition and nitrogen of foxtail (Italian) millet (Setaria italica) grain of different varieties

The amino acid composition of 13 samples of foxtail millet (Setaria italica L) from six Chinese and one French varieties was determined as a function of their N content (N), which ranged from 1·82 to 3·65 g per 100 g of grain DM. The levels of amino acids in grain DM increased linearly with N with correlation coefficients close to 1 for most of them regardless of foxtail millet genotype or phenotype. Thus simply knowing N enables one to predict the amino acid composition of any foxtail millet grain sample. Amino acids in crude protein of grain (g 16 g^?1N)changed as quadratic functions of N, which decreased for glycine, cysteine, tysine, histidine and arginine, remained nearly constant for valine, threonine, tyrosine, methionine and aspartate plus asparagine, and increased for other amino acids. Foxtail millet appeared as the only cereal in which lysine is the only limiting essential amino acid. However, the lysine score was low and intermediate between that of maize and sorghum, falling from 48 to 31 % when N increased from 1·82 to 3·65 g per WO g DM. The N-to-protein conversion factor strongly increased with N and was the highest of all cereals within the N range studied. The results also showed that the composition of storage proteins accumulated in grains remained constant, with a prolamin to glutelin ratio close to three and independent of grain protein content.     

A quantitative analysis of amino acid accumulation in developing grain of normal and Opaque-2 maizes

From previous observations concerned with the qualitative and quantitative evolution of protein groups in developing maize (Zea mays L.) grain, it may be deduced that the amount per grain of any amino acid incorporated into the proteins is linearly related to the amount of true protein in the grain. In this study, such a linear relationship is characterised quantitatively from experimental data by regressing the individual amino acid against the total protein accumulated in the developing grain of both normal (+) and opaque-2 (o2) maize. The linear least squares regression on total nitrogen content in the grain is also used for specifying the quantitative variations of any free and protein-incorporated amino acid in the grain. The slope B_j of the regression line represents the relative rate of accumulation of amino acid (j) in grain protein (or nitrogen) and its limiting content in protein (or nitrogen) of a grain which accumulates a large amount of it. B_j, which is compared to the amount of amino acid (j) present in the protein of immature grains, or of mature endosperm, or germ, is close to the amount of amino acid (j) present in the protein of mature endosperm. The same holds for the B_j value determined from opaque-2 maize and which differs from the amount of B_j determined using the normal variety for many amino acids. Using experimental data reported in the literature, a linear relationship has also been found in describing quantitative variations of amino acid in the developing grain of normal and Hiproly barley.     

Variation in protein and trypsin inhibitor activity with maturity and amino acid composition of winged bean (Psophocarpus tetragonolobus) seeds

The protein and trypsin inhibitor activity in pods and seeds of winged bean (Psophocarpus tetragonolobus (L) DC) increase, and in the pod hull decrease, with the maturity of plant. The seeds of 21 cultivars both exotic and of Indian origin cultivated on marginal alkaline soil (pH 8.7) were analysed for protein (36.4–45.3) and amino acid composition (lysine 4.8 to 6.7).     

Effect of potassium,magnesium and sulphur applied in different forms of fertilisers on free amino acid content in leaves of tea (Camellia sinensisL)

Free amino acids in tea leaves are important chemical constituents that considerably influence the quality of tea, especially that of green tea. The present study was conducted to investigate the effects of the nutrients potassium, magnesium and sulphur on biomass production and amino acid accumulation in tea leaves in pot and field experiments. The results show that biomass production and the free amino acid contents in tea leaves increased considerably following the application of potassium and magnesium. Combined application of both nutrients produced the highest increment in free amino acids. The increased free amino acid content in tea leaves was accompanied by enhanced nitrate reductase activity. This indicates that potassium and magnesium application improved the nitrogen metabolism, leading to an increased synthesis of amino acids. A comparison between K₂CO₃ vs K₂SO₄ and MgO vs MgSO₄ revealed significantly higher amino acid contents in tea leaves when both potassium and magnesium were applied in the sulphate form, indicating that not only potassium and magnesium but also sulphur plays an important role in the accumulation of amino acids in tea leaves. A pot experiment using KCl and K₂SO₄ was carried out in order to compare the two commercially available potassium fertiliser forms in their effect on biomass production and the content of free amino acids in tea leaves. The results showed no difference on biomass production between the two fertiliser forms. However, whereas KCl tentatively depressed nitrate reductase activity and hence the accumulation of free amino acids, K₂SO₄ significantly increased the contents of these quality promoting constituents of tea leaves. The role of fertiliser composition, detrimental effects of accompanying anions, eg Cl⁻ and differences in nutrient availability (eg oxide≪sulphate form) and possible impact on soil chemistry as main reasons for the observations, being crucial aspects with regard to fertilisation of tea for good quality are discussed. © 1998 SCI.     

Kinetics of free protein amino acids, free non-protein amino acids and trigonelline in soybean (Glycine max L.) and lupin (Lupinus angustifolius L.) sprouts

A contribution for a better nutritional knowledge of lupin (Lupinus angustifolius L. var. zapaton) and soybean (Glycine max L. var. merit and var. jutro) sprouts about free protein amino acids (FPAA), free non-protein amino acids (FNPAA such as β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), α-aminoadipic acid, γ-aminobutyric acid (GABA) and β-alanine) and trigonelline content has been carried out. Seeds were germinated at 20 °C and darkness during several days in order to obtain good appearance sprouts. The content of FPAA and FNPAA varied among species and varieties. FPAA increased dramatically during germination and the lowest concentrations were found for G. max L. var. jutro. Cys was not detected as FPAA in seeds and seedlings of both legumes. Asn was present in the highest amounts in soybean and lupin seedlings. The α-aminoadipic acid gliotoxin, which was not present in raw soybean seeds, appeared in low amounts during germination. Later stages of germination caused significant increases of β-alanine and GABA, amino acids with beneficial properties. Germination also affected the content of the multifunctional plant hormone trigonelline and slight changes were observed. Highest levels of FPAA, beneficial FNPAA and trigonelline were found at 4, 6 and 9 days of germination for G. max L. var. jutro, G. max L. var. merit and L. angustifolius L. var. zapaton, respectively. Furthermore, these selected germination conditions showed low levels of the gliotoxic α-aminoadipic acid ensuring nutritional safety of the studied seedlings.     

Amino acid composition of storage proteins of a promising chickpea (Cicer arietinum L) cultivar

The amino acid compositions of flours made from the cotyledons and from the whole seeds of a disease-resistant, stable and high-yielding cultivar of chickpea (Cicer arietinum L) cv H75–35, known locally as Gaurav, have been analysed. These, together with similar analyses of the albumin, globulin, legumin and vicilin protein fractions, have been compared with those of other legumes. Seed protein content was 19·8 % with globulin constituting 62·4 % of the total seed protein. The ratios of albumin to globulin and legumin to vicilin were 1:4 and 6:1, respectively. The proportion of basic amino acids in the albumin was low whereas the reverse was true in the globulin. The legumin fraction seems to be superior in terms of total essential amino acids to those from other sources. Sulphur amino acids were the most limiting, followed by tryptophan or threonine depending on the fraction. However, the ratio of methionine to cystine was high (2·76:1). The extent of the sulphur amino acid deficiency was assessed, and possible approaches for its improvement are outlined.