Analysis of acetylation in the two histone H3 variants of alfalfa by acid/urea/Triton-polyacrylamide gel electrophoresis has established that the minor variant H3.2 has a 2-fold higher level of ...acetylation than the major variant H3.1. Purification and sequence analysis of both variants showed sequence identity across the complete amino-terminal domain, which contains the 6 modified lysines 4, 8, 14, 18, 23, and 27. The two proteins have different distributions for acetylation: mono-, di-, and tri-methylation. The higher level of acetylation of H3.2 was confirmed in a wider pattern across all 6 lysines. Lysine modification levels varied for all sites in both proteins between 5 and 95%, with combinations of one to four types of modification co-existing at each residue. Additional sequence analysis of the H3.1 and H3.2 proteins and of tryptic core peptides established that the two histones differ only in residues 31, 41, 87, and 90. This indicates that major histone H3.1 is the product of the major alfalfa histone H3 gene and makes it likely that H3.2 is the product of the minor H3 gene, known from a partial cDNA clone. The variant-specific differences in lysine modifications in protein domains with identical primary structures suggest that the pattern and level of lysine modifications may be directed by the distinct chromatin environments of the two histone H3 variants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A series of experiments were conducted to compare the susceptibility of P. regina larvae reared in isolation or in groups to the effects of diet-borne metabolic inhibitors: chlorogenic acid (CGA) and ...mimosine. Larvae were presented with diets containing 0.4 mM CGA or 0.4 mM CGA in combination with 22 mM lysine or methionine or with diets containing 1.5, 15 or 30 mM concentrations of mimosine. Methionine and CGA caused significantly reduced pupal weights when compared with larvae presented with lysine and CGA. All concentrations of mimosine resulted in 100 % mortality with larvae unable to successfully complete pupation even at the lowest concentration. In general, larvae reared in groups were less susceptible to the toxic effects resulting from dietborne metabolic inhibitors. The results are discussed in relation to the chemical factors that result from the feeding activity of saprophagous dipterans.
For human nutrition the main source of vegetable proteins are cereal and legume seeds. The content of total soluble amino acids in mature endosperm of wild-type, opaque and floury maize (Zea mays L.) ...mutants were determined by HPLC. The total absolute concentration of soluble amino acids among the mutants varied depending on the mutant. The o11 and o13 mutants exhibited the highest average content, whereas o10, fl3 and fl1 exhibited the lowest average content. In general, the mutants exhibited similar concentrations of total soluble amino acids when compared to the wild-type lines, with the clear exception of mutants o11 and fl1, with the o11 mutant exhibiting a higher concentration of total soluble amino acids when compared to its wild-type counterpart W22 and the fl1 mutant a lower concentration when compared to its wild-type counterpart Oh43. For methionine, the mutants o2 and o11 and wild-type Oh43 exhibited the highest concentrations of this amino acid. Significant differences were not observed between mutants for other amino acids such as lysine and threonine. The high lysine concentrations obtained originally for these mutants may be due to the amino acids incorporated into storage proteins, but not those present in the soluble form.
A principal fonte de proteínas vegetais para alimentação humana e animal é fornecida pelos grãos de cereais e leguminosas. O conteúdo de aminoácidos solúveis totais foi determinado por HPLC em endospermas de milho (Zea mays L.) normal e mutantes opaco e floury. A concentração de aminoácidos solúveis totais variou entre os mutantes. Os mutantes o11 e o13 se destacaram com médias superiores, enquanto que mutantes o10, fl3 e fl1 apresentaram as menores médias. De maneira geral, para a concentração total de aminoácidos solúveis, os grãos dos mutantes foram similares aos seus tipos selvagens com exceção dos mutantes o11 e fl1 sendo que o primeiro apresentou valor maior que seu tipo selvagem W22, enquanto que o fl1 teve valor menor que o Oh43. Para metionina, os mutantes o2 e o11 e o tipo selvagem Oh43 apresentaram as mais altas concentrações deste aminoácido. Valores similares foram observados entre os mutantes e os tipos selvagens para concentração de outros aminoácidos analisados, tais como lisina e treonina. As altas concentrações sugeridas originalmente para estes mutantes devem ser devidas aos níveis destes aminoácidos incorporados nas proteínas de reserva, mas não na forma solúvel.
Amino acids interact with carbohydrates to form Maillard browning products. Such reactions reduce the nutritional value of foods containing amino acids and carbohydrates and may lead to the formation ...of compounds that are mutagenic and clastogenic or chromosome-damaging. A need therefore exists to inhibit these heat-induced interactions. To demonstrate whether SH-containing sulfur amino acids minimize nonenzymatic browning, beta-alanine, N alpha-acetyl-L-lysine, glycylglycine, and a mixture of amino acids were each heated with glucose in the absence and presence of the following potential inhibitors: N-acetyl-L-cysteine, L-cysteine, reduced glutathione, sodium bisulfite, and urea. Inhibition was measured as a function of temperature, time of heating, and concentration of reactants. The extent of browning was estimated by absorbance measurements at 420 nm. Inhibition was independent of the amino group containing reactant. The minimum concentrations for optimum inhibition, in moles of inhibitor per mole of D-glucose, were as follows: sodium bisulfite, 0.02; L-cysteine, 0.05; N-acetyl-L-cysteine, 0.2; reduced glutathione, 0.2; urea, 8. An "index of prevention" (IP) was used to calculate the inhibition at the optimum mole ratio range, where IP = 100 - molar absorptivity value (MAV) of the amine compound + glucose + inhibitor X 100/(MAV of the amine compound + glucose). The calculated values were about 90% in all cases. Possible mechanisms of browning prevention are discussed
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The PsaD subunit of photosystem I (PSI) is a peripheral protein that provides a docking site for ferredoxin and interacts with the PsaB, PsaC, and PsaL subunits of PSI. We used site-directed ...mutagenesis to determine the function of a basic region in PsaD of the cyanobacterium Synechocystis sp. PCC 6803. We generated five mutant strains in which one or more charged residues were altered. Western blotting showed that replacement of lysine (Lys)-74 with glutamine or glutamic acid led to a substantial decrease in the level of PsaD in the membranes. The mutant PSI complexes showed reduced NADP+ photoreduction activity mediated by ferredoxin; the decrease in activity correlated with the reduced level of PsaD. Using protein synthesis inhibitors we showed that the degradation rates of the mutant and wild-type PsaD were similar, indicating a defect in the assembly of the mutant protein. Treatment of the mutant PSI complexes with a different concentration of NaI showed that the mutations decreased affinity between PsaD and the transmembrane components of PSI. With glutaraldehyde, the mutant and wild-type PsaD proteins could be cross-linked with PsaC, but the PsaD-PsaL cross-linked product was reduced drastically when arginine-72, Lys-74, and Lys-76 were mutated simultaneously. These studies demonstrate that the basic residues in the central region of PsaD, especially Lys-74, are crucial in the assembly of PsaD into the PSI complex
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Experiments (Exp.) were conducted with Cornish Rock males (4 to 14 or 15 d of age) to determine the Lys requirement (Exp. 1) and the optimum ratio of TSAA:Lys for chicks fed adequate or inadequate ...Lys (Exp. 2). In Exp. 1, 180 chicks were allotted on the basis of BW to six treatments with six replications of five chicks each in a completely randomized design (CRD). Average initial and final BW were 73.5 and 415.5 g. The Lys levels fed were: 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3% digestible Lys. In Exp. 2, 240 chicks were allotted on the basis of BW to 12 treatments with four replications of five chicks each in a CRD. Average initial and final BW were 68.5 and 336.3 g. Chicks were fed either 0.82 or 1.0% digestible Lys and within each Lys level, a ratio of TSAA:Lys of: 0.55, 0.63, 0.72, 0.80, 0.88, and 0.96, resulting in a 2 X 6 factorial arrangement of treatments. At the end of each trial, all chicks were weighed and pen feed consumption was measured. In Exp. 1, average daily gain (ADC) and gain:feed (CF) increased (linear, P 0.01; quadratic, P 0.02) as dietary Lys increased. A cubic (P 0.04) effect of Lys for average daily feed intake (ADFI) was observed. One-slope, broken-line regression models estimated Lys requirements of 1.0, 0.9, and 1.1% for ADG, ADFI, and GF, respectively. In Exp. 2, chicks fed 1.0% Lys had higher (P 0.01) ADG, ADFI, and GF than chicks fed 0.82% Lys. Daily gain, ADFI, and GF increased (linear, P 0.01; quadratic, P 0.01) as TSAA:Lys increased. For ADG, ADFI, and GF, one-slope, broken-line regression models estimated required ratios of TSAA:Lys of 0.66, 0.71, and 0.63 for chicks fed 1.0% Lys and 0.66, 0.67, and 0.63 for chicks fed 0.82% Lys There were no differences (P 0.05) in the estimated ratios of TSAA:Lys required to maximize ADG, ADFI, and GF for chicks fed 0.82 and 1.0% Lys. Thus, similar ratios of an indispensable amino acid to Lys can be obtained when chicks are fed at or slightly below their Lys requirement
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Content of furosine in infant formulae and follow-on formulae Martysiak-Zurowska, D.,Gdansk Technical University (Poland). Dept. of Food Chemistry Technology and Biotechnology; Stolyhwo, A.,Warsaw Agricultural University (Poland). Faculty of Human Nutrition and Consumer Sciences
Polish journal of food and nutrition sciences,
(2007), 2007, Volume:
57, Issue:
2
Journal Article
Peer reviewed
The determination of the furosine (FUR) indicator of the Maillard reaction in commercial infant formulae (IF), follow-on formulae (FF), human milk and raw cow milk was performed using high ...performance liquid chromatography with ultraviolet detection (HPLC/UV). A high FUR content was confirmed that ranged from 1320+-102.2 to 1550.9+-166.5 mg/100 g protein in infant formulae IF and from 931.9+-153.8 to 1156.7+-104.5 mg/100 g protein in follow-on formulae FF (human milk - at the average below 6 mg/100 g protein). Such a significant difference between FUR values of commercially available formulas is accounted for imperfection of different technologies of manufacturing IF and FF. In dairy products damage caused by heat treatment could be greater as a result of manufacturing processes and storage conditions. Furosine content was used in order to calculate the concentration of blocked lysine. In infant formulas IF's the blocked lysine levels were found to range from 19.6 to 34 percent of total lysine. Taking into consideration harmful for health, toxic products of Mallard reaction, the content of FUR should be labelled. The content of furosine tolerance should make compromise between that what is theoretical demanded and that what is practical reached (fresh milk powder for all purposes - about 120 mg FUR/100 g protein, FF of producer C - 930 mg FUR/100 g protein)
Ten crossbred gilts fitted with simple T-cannulas at the distal ileum were used to determine the apparent and true ileal amino acid digestibilities in five different soybean products: extruded, ...jet-sploded, micronized, or roasted full-fat soybeans (FFSB) and soybean meal (SBM). The gilts with an average initial body weight of 36 kg were fed the different diets according to a replicated 5 x 5 Latin square design. Gilts were fed twice daily at 0800 and 1830 at 2.6 times maintenance energy requirement. All diets were cornstarch-based and formulated to contain 16% CP from one of the five soybean products. The recovery of endogenous lysine at the distal ileum was determined using the homoarginine technique. This technique involved the guanidination of dietary lysine to homoarginine, to allow for a differentiation between undigested dietary lysine, represented by homoarginine, and endogenous lysine in the digestive tract of pigs consuming diets that contain guanidinated proteins. Chromic oxide and dysprosium chloride were included as indigestible markers in the normal and homoarginine diets, respectively. True digestibilities were only determined with the five gilts of one Latin square. Ileal digesta were collected for 24 h on d 8 and 10 of each 10-d experimental period. The apparent ileal protein digestibility was higher in SBM than in other soybean products (P 0.05). In the heat-treated FFSB, the apparent protein digestibility varied between 69.0 and 81.6%. Recovery of endogenous lysine was affected by the diet (P 0.01) and varied between 1,329 and 2,448 mg/kg of DM intake. True lysine digestibility was higher in SBM (P 0.05) than in roasted or jet-sploded FFSB; extruded and micronized FFSB were intermediate. With the exclusion of extruded FFSB, protein nitrogen flows were higher when FFSB were fed than when SBM was fed (P 0.05). Free amino acid nitrogen flows expressed as a percentage of total amino acid nitrogen flow were not influenced by treatment (P 0.05)
Spinach (Spinacea oleracea) leaf ferredoxin (Fd)-dependent nitrite reductase was treated with either the arginine-modifying reagent phenyl-glyoxal or the lysine-modifying reagent ...pyridoxal-5'-phosphate under conditions where only the Fd-binding affinity of the enzyme was affected and where complex formation between Fd and the enzyme prevented the inhibition by either reagent. Modification with 14Cphenylglyoxal allowed the identification of two nitrite reductase arginines, R375 and R556, that are protected by Fd against labeling. Modification of nitrite reductase with pyridoxal-5'-phosphate, followed by reduction with NaBH4, allowed the identification of a lysine, K436, that is protected by Fd against labeling. Positive charges are present at these positions in all of the Fd-dependent nitrite reductases for which sequences are available, suggesting that these amino acids are directly involved in electrostatic binding of Fd to the enzyme
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