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1.
Protein distribution in endosperm of maize grains differing by their texture, flint or dent, and by their genotype, wild or waxy or amylose-extender, was examined by the successive use of 0.5 M NaCl, 0.5 M NaCl plus 0.6% 2-mercaptoethanol (2ME) at neutral and then alkaline pH, and 55% 2-propanol plus 0.6% 2ME as extractants. Proteins extracted in the presence of 2ME were characterized by their size polymorphism and amino acid composition. Proteins isolated with NaCl plus 2ME at neutral pH corresponded with a mixture of gamma-zein (27 kDa) and glutelin-like proteins. Proteins isolated with NaCl plus 2ME at pH 10 were a mixture of gamma-zeins (27 and 16 kDa) and beta-zeins (14 kDa). Alcohol-soluble proteins consisted of alpha-, beta-, and delta-zeins, alpha subunits being predominant. Zein quantitation was improved by weighing the nitrogen percentage of extracts by their zein content, as estimated from the data on amino acid composition. The data reported by Wolf et al. (Cereal Chem. 1975, 52, 765) were integrated to the results of this work to suggest the occurrence of an inverse correlation between amylose in starch and zeins in proteins.  相似文献   

2.
Alpha‐amino nitrogen compounds of floury and vitreous parts of hand‐dissected endosperm from eight maize (Zea mays L.) inbred lines, representing a broad range of vitreousness (42–95%), were isolated as nonprotein nitrogen, albumin‐globulins, zeins, and true glutelins. The three protein classes averaged, respectively, 13, 48, and 35% of total nitrogen in floury endosperm, and 4, 79, and 15% of that in vitreous endosperm. For six inbreds, floury endosperm was richer in 27 kDa γ‐zein than vitreous endosperm; the reverse was found for an Argentine flint inbred (ARGL 256), and only traces of 27 kDa γ‐zein occurred in both floury and vitreous endosperm of inbred F113. Results were compared with protein distribution patterns reported in the literature of whole endosperm of wild‐type and mutant genotypes of maize, and with wild relatives of maize, Tripsacum, and teosintes. When percentage of salt‐soluble nitrogen increased from 2% (Tripsacum) to 22% (in double mutant Oh43o2;bt2), zeins decreased from 87 to 22%, and true glutelins increased from 11 to 57%. The pattern of whole endosperm of Zea perennis was very similar to that of the vitreous endosperm of line ARGL 256. The mean pattern for whole endosperm of six o2 inbred lines was identical to that of floury endosperm of eight wild‐type lines, consistent with a lack of synthesis of α‐zeins due to the mutation in the O2 gene.  相似文献   

3.
The protein distribution in five gluten samples isolated during and after wet-milling of maize grains (slurry before and after filtration, total industrial gluten meal, and coarse and fine fractions obtained after sieving) was investigated by sequential extraction. Six fractions (FI-FVI), including residue, were isolated. Heating filtered slurry to draw water away did not alter protein distribution. Compared with values reported in the literature for endosperm protein, we found a decrease in FI and FIV, respectively, extracted with salt alone and with reductant, due to proteolysis and partial elimination of nonprotein nitrogen during slurry filtration, and an increase in FII and decrease in FIII, alcohol-soluble proteins extracted without and with reductant, respectively, due to the presence of SO2 in the steeping liquor. Gluten, with respect to the endosperm from which it originated, was richer in zeins (FII + FIII) and glutelins (FV + FVI) due to partial removal of salt-soluble proteins (FI + FIV) during the isolation process.  相似文献   

4.
中华猕猴桃耐盐变异体筛选   总被引：8，自引：2，他引：8  
取中华猕猴桃(Actinidia chinensis)101品系试管苗叶片为外植体,诱导愈伤组织,将愈伤组织移入含NaCl的MS培养基选择8次,培养基内NaCl的浓度逐步增加,γ射线作为诱变剂,已筛选出耐0.5％、0.7％、1.0％NaCl的变异细胞系,并均再生出完整植株。试验结果表明:1.MS+0.5ppm 2,4-D+1.0ppm Zt是最佳的脱分化培养基;MS+1.0ppm Zt+0.2ppm IBA是最佳的分化培养基;生根培养基可采用MS+0.5ppm IBA。2.0.5％NaCl可作为耐盐筛选的盐分临界值。3.γ射线处理对愈伤组织的生长及细胞的大小均有显著的影响,5kR可作为变异体筛选的诱变照射量。  相似文献   

5.
The conventional Landry‐Moureaux method for selective extraction of maize proteins was modified by reducing the contact time of meal with extractants and by removing 55% 2‐propanol as extractant. The new procedure, coupled with a method for quantitating protein at microgram level, was used for assessing the nitrogen distribution of four soluble protein fractions present in 100‐mg samples of endosperm originating from six maize inbreds and opaque‐2 versions. Proteins extracted with 55% 2‐propanol plus reductant were made up of α‐, β‐, γ‐, and δ‐zeins. Proteins extracted subsequently with salt plus reductant were minor and poor in lysine (1 mol%).They were associated with zeins. Comparison of present data with those available in the literature showed a close similarity for a given genotype between the percentage of total α‐amino nitrogen extracted by 2‐propanol plus reductant than by salt plus reductant under conditions of the modified procedure and that of total Kjeldhal nitrogen extracted by 2‐propanol with and without reductant, and by salt plus reductant, using the conventional procedure. A simplified protocol was described and tested for isolating and quantitating α‐amino nitrogen as nonprotein, true protein, salt‐soluble proteins, zeins, and true glutelins in any sample of maize endosperm.  相似文献   

6.
Zein isolation by aqueous ethanol extraction from dry-milled corn produces a mixture of zeins, covalently linked polymers (dimers, tetramers, etc.) and higher-molecular-weight aggregates, some of which were not soluble in aqueous alcohol. The insoluble particles were identified as protein aggregates which form when the extraction solution is heated, particularly under alkaline conditions. The insoluble protein aggregates were not present in zein isolated by the same method from corn gluten meal. Zeins extracted from corn gluten meal and dry-milled corn were fractionated (by differential solubility) to identify differences in their polypeptide compositions. Using polyacrylamide gel electrophoresis, beta- and gamma-zeins were detected in dry-milled corn, but only trace amounts of beta-zein were found in corn gluten meal. Treatment of dry-milled corn with 0.55% lactic acid and 0.2% sulfur dioxide at 50 degrees C for 6 h before ethanol extraction resulted in a 50% increase in zein isolate yield with high solubility (98%). This pre-extraction treatment cleaved disulfide linkages of the beta- and gamma-zeins and significantly reduced insoluble aggregates in zein isolates.  相似文献   

7.
A rapid, ion-exchange method that isolates thermostable pectinmethylesterase (TS-PME) from Marsh grapefruit pulp is presented. TS-PME was selectively extracted with 1 M NaCl and equilibrated at low pH (3.1 +/- 0.04). After dilution to a final concentration of 50 mM acetate buffer, pH 5.5, and 0.1, 0.25, or 0.5 M NaCl, the extract was applied to an ion-exchange column without ammonium sulfate precipitation and dialysis. The percent yield varied from an average of 70% (0.1 M NaCl) to 14% (0.5 M NaCl), with a specific activity of >400 U/mg protein in the latter sample. TS-PME activity of some column fractions varied compared with crude extracts before column separation. Some fractions lost thermostability after separation if loaded at 0.1 M or 0.25 M NaCl. In extracts that were loaded at 0.5 M NaCl, the TS-PME activity was significantly higher than that observed in the heated crude extracts. Ion-exchange chromatography may have separated an unidentified protective factor in PME fractions.  相似文献   

8.
Two high lysine maize endosperm mutations, opaque-5 (o5) and opaque-7 (o7), were biochemically characterized for endosperm protein synthesis and lysine metabolism in immature seeds. Albumins, globulins, and glutelins, which have a high content of lysine, were shown to be increased in the mutants, whereas zeins, which contain trace concentrations of lysine, were reduced in relation to the wild-type lines B77xB79+ and B37+. These alterations in the storage protein fraction distribution possibly explain the increased concentration of lysine in the two mutants. Using two-dimensional polyacrylamide gel electrophoresis of proteins of mature grains, variable amounts of zein polypeptides were detected and considerable differences were noted between the four lines studied. The analysis of the enzymes involved in lysine metabolism indicated that both mutants have reduced lysine catabolism when compared to their respective wild types, thus allowing more lysine to be available for storage protein synthesis.  相似文献   

9.
田间小区试验条件下,研究了喷施不同组合的铁锌混合肥对豌豆子粒(Pisum.sativum.L)中铁、锌含量及其营养品质的影响。结果表明,喷施含铁混合肥(0.1%FeSO4+0.2%腐殖酸+0.5%尿素)能显著提高豌豆子粒中Fe含量,但对其累积Zn有不利影响;喷施含锌混合肥(0.2%ZnSO4+0.1%腐殖酸+0.5%尿素)能显著增加豌豆子粒中Zn含量,但对其累积Fe亦有一定的抑制作用。本试验条件下,豌豆子粒铁锌混合肥最优肥料组合为:0.1%FeSO4+0.2%ZnSO4+0.2%腐殖酸+0.5%尿素。铁锌混合肥不但能显著提高豌豆子粒中铁、锌的含量,还能显著提高维生素C和可溶性糖的含量,降低硝态氮的含量,改善营养品质。  相似文献   

10.
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11.
Cell wall material was extracted by five different methods from an oenological strain of Saccharomyces cerevisiae. Enzyme preparations containing beta-glucanase activity (Zymolyase, Glucanex, and Finizym 250L) allowed a better extraction yield compared to that of dithiothreitol (DTT) and EDTA. The yeast extracts were only soluble in part in wine. The wine-soluble fraction (WSF) of the five extracts, differing in both protein and sugar contents, when added in increasing amounts to white wine differently affected protein haze formation, as determined by the heat test, giving dose/response curves of different shapes. The curves obtained with the WSF derived from DDT and Zymolyase extracts showed a plateau value corresponding to 90% and 80% of wine haze reduction, respectively. In contrast, addition of the WSF derived from the other extracts resulted in increased turbidity with respect to the original wine. The mannoproteins (MP), isolated from each yeast extract by Concanavalin-A chromatography, gave dose/response curves showing shapes more similar among them than those obtained with the whole WSFs. The best wine stabilization was obtained with the MP of the DTT and Zymolyase extracts. The supernatants obtained after heating the MP of the different extracts were also tested. The stabilizing effect of the heat-stable MP (HSMP) was always larger than that of the corresponding total (un-heated) MP. The HSMP obtained starting from the DTT and Zymolyase extracts showed the best haze-protecting effect, which was, however, lower than that obtained with their corresponding WSF. This result suggests that wine protein stabilization by compounds of the yeast cell wall could be related, in addition to the action of the MP, also to the presence of other substances of different nature.  相似文献   

12.
Malted cereals are rich sources of alpha-amylase, which catalyzes the random hydrolysis of internal alpha-(1-4)-glycosidic bonds of starch, leading to liquefaction. Amylases play a role in the predigestion of starch, leading to a reduction in the water absorption capacity of the cereal. Among the three cereal amylases (barley, ragi, and jowar), jowar amylase is found to be the most thermostable. The major amylase from malted jowar, a 47 kDa alpha-amylase, purified to homogeneity, is rich in beta structure ( approximately 60%) like other cereal amylases. T(m), the midpoint of thermal inactivation, is found to be 69.6 +/- 0.3 degrees C. Thermal inactivation is found to follow first-order kinetics at pH 4.8, the pH optimum of the enzyme. Activation energy, E(a), is found to be 45.3 +/- 0.2 kcal mol(-)(1). The activation enthalpy (DeltaH), entropy (DeltaS*), and free energy change (DeltaG) are calculated to be 44.6 +/- 0.2 kcal mol(-)(1), 57.1 +/- 0.3 cal mol(-)(1) K(-)(1), and 25.2 +/- 0.2 kcal mol(-)(1), respectively. The thermal stability of the enzyme in the presence of the commonly used food additives NaCl and sucrose has been studied. T(m) is found to decrease to 66.3 +/- 0.3, 58.1 +/- 0.2, and 48.1 +/- 0.5 degrees C, corresponding to the presence of 0.1, 0.5, and 1 M NaCl, respectively. Sucrose acts as a stabilizer; the T(m) value is found to be 77.3 +/- 0.3 degrees C compared to 69.6 +/- 0.3 degrees C in the control.  相似文献   

13.
适量施氮增强盐胁迫下高羊茅生长和抗氧化能力   总被引：2，自引：0，他引：2  
为土壤盐渍地区高羊茅(Festuca arundinacea)草坪的合理施肥,该研究用NaCl浓度为0,70,140mmol/L和不同NH4NO3水平(质量浓度为0.01,0.6,1.2g/L)对盆栽高羊茅植株进行交互处理,并测定处理后其生长量和抗氧化能力。结果表明,同一水平NH4NO3相比,NaCl胁迫下高羊茅鲜质量、干质量、含水率均低于无NaCl处理;而根系脱氢酶活性、硝酸还原酶(nitratereductase,NR)活性、超氧化物歧化酶(superoxidedismutase,SOD)同工酶活性NO3-含量、质膜透性和丙二醛(malonicdialdehyde,MDA)含量均强于或高于无NaCl处理;CAT(catalase,CAT)同工酶活性及蛋白表达量发生改变。同一浓度NaCl胁迫下,随NH4NO3水平增加,其鲜质量、干质量、含水率呈上升趋势;NO3-含量、质膜透性和MDA含量呈下降趋势;SOD同工酶增强;根系脱氢酶活性、NR活性、CAT同工酶活性和蛋白表达量增强幅度明显减弱。因此,与NH4NO30.01g/L相比,NH4NO30.6g/L改善了同浓度盐胁迫下高羊茅氮素营养、抗氧化能力和蛋白质表达量,增强了其耐盐性;而NH4NO31.2g/L能一定程度上改善其氮素营养,但根系主动吸收离子能力、清除H2O2能力和蛋白质表达量增强有限,引起根际环境NH4NO3积累,严重导致土壤次生盐渍化。该研究为盐渍土壤上的高羊茅草坪合理施用NH4NO3提供参考。  相似文献   

14.
为正确表征云南文山三七种植区土壤中植物可利用态砷,选取NaH2PO4（0.5mol·L-1）、H2O、H3PO4（0.2mol·L-1）、EDTA（0.0625mol·L-1,pH=7）、NH4C（l1.0mol·L-1）和（NH4）2SO（40.05mol·L-1）6种提取剂,比较了它们对土壤中砷的提取效果,及其所提取的砷与三七植株各部位砷含量之间的相关关系。结果表明,NaH2PO4、H3PO4和（NH4）2SO4这3种提取态砷与土壤总砷呈极显著正相关,相关系数分别为0.8359、0.8177和0.8810。NaH2PO4和H3PO4的提取效率较高,平均提取效率分别为6%和11%;而（NH4）2SO4提取效率较低,平均仅为0.084%。NaH2PO4和（NH4）2SO4提取态砷与三七主根、须根和茎部砷含量呈显著正相关,H3PO4提取态砷与三七主根和须根砷含量呈显著正相关。综合考虑认为NaH2PO（40.5mol·L-1）是最佳提取剂,H3PO（40.2mol·L-1）提取剂次之,这两种提取剂均可较好地表征土壤中砷的三七可利用性。  相似文献   

15.
Extracts from different parts of Melia azedarach L. were studied as potential antifungal agents for selected phytopathogenic fungi. In a serial agar dilution method, hexanic and ethanolic extracts from fruit, seed kernels, and senescent leaves exhibited fungistatic activity against Aspergillus flavus,Diaporthe phaseolorum var. meridionales, Fusarium oxysporum, Fusarium solani, Fusarium verticillioides, and Sclerotinia sclerotiorum. Both hexanic extract from senescent leaves and ethanolic extract from seed kernel were highly effective on all tested fungi, with minimum inhibitory concentration (MIC) values ranging from 0.5 to 25 mg/mL and 0.5 to 5 mg/mL, respectively. In addition, all of the above-mentioned extracts showed fungicidal activity on these fungi, with ethanolic seed kernel extract being the most active. Three compounds displaying activity against F. verticillioides were isolated from the ethanolic seed kernel extract and were characterized as vanillin (1), 4-hydroxy-3-methoxycinnamaldehyde (2), and (+/-)-pinoresinol (3), with MICs of 0.6, 0.4, and 1.0 mg/mL, respectively. These compounds also showed a synergistic effect when combined in different concentrations, needing four times less concentration to reach complete inhibition in the growth of F. verticillioides.  相似文献   

16.
Despite the wide availability of liquid herbal extracts using mixtures of alcohol, glycerin, and water, or glycerin and water as solvents, no data on the chemical composition of such extracts is readily available. In this study, the amount and the stability of the major saponins in Panax quinquefolius root extracts, made either with 50% (v/v) aqueous ethanol, a mixture (v/v/v) of 20% ethanol, 40% glycerin, and 40% water, or with 65% (v/v) aqueous glycerin, were evaluated by HPLC-UV analysis. The amount of total saponins was highest in the 50% aqueous ethanol extract (61.7 +/- 0.1 mg/g dry root), although similar to the ethanol-glycerin-water extract (59.4 +/- 0.5 mg/g dry root). Saponins were significantly lower in the 65% aqueous glycerin extract (51.5 +/- 0.2 mg/g dry root). Interestingly, the amounts of individual saponins were quite variable depending on the solvent. This is in part due to enzymatic cleavage of ginsenosides in the glycerin containing extracts during the maceration process. Storage of the extracts at 25 degrees C over the period of a year led to a 13-15% loss of saponins with all three types of extractions.  相似文献   

17.
Two new piperidine amides, N-[(2E,4E,8Z)-tetradecatrienoyl]piperidine (1) and N-[(2E,4E,8Z,11Z)-tetradecatetrenoyl]piperidine (2), along with the known metabolites N-[(2E,4E)-tetradecadienoyl]piperidine (3), N-isobutyl-(2E,4E,)-tetradecadienamide (4), N-isobutyl-(2E,4E,8Z)-tetradecatrienamide (5), N-isobutyl-(2E,4E,8Z,11Z)-tetradecatetraenamide (6), sesamine (7), pinoresinol (8), and espeletone (9), were isolated from the dichloromethane/methanol extracts of the plant Otanthus maritimus Hoffman & Link collected from coastal areas in Greece. Pinoresinol (8) and espeletone (9) are reported for the first time as metabolites of O. maritimus. The structures of the new natural products were elucidated by interpretation of their NMR and high-resolution mass spectral measurements. The insecticidal properties of the crude extracts, essential oil, and isolated metabolites 1-9 were evaluated on Crematogaster scutellaris (Olivier) ants and Reticulitermes balkanensis (Clement) termites, showing significant levels of activity.  相似文献   

18.
欧洲鹅耳枥幼苗对盐胁迫的生长及生理响应   总被引：1，自引：0，他引：1       下载免费PDF全文
[目的]探讨欧洲鹅耳枥(Carpinus betulus)对盐胁迫的响应及其耐盐性。[方法]以两年生欧洲鹅耳枥幼苗为材料,用不同浓度NaCl(0%,0.1%,0.2%,0.3%,0.4%,0.5%)溶液处理幼苗,研究不同盐分胁迫对其幼苗生长及生理生化指标的影响。[结果](1)随着盐胁迫的加剧,欧洲鹅耳枥幼苗受到损害程度逐渐加重,相对苗高生长、相对地径生长和总干重均呈下降趋势,而根冠比则逐渐增大;(2)叶片相对含水量随着盐胁迫程度的增加而下降,且盐浓度越高,时间越久,变化幅度越大;(3)叶片叶绿素总量、SOD活性、POD活性、可溶性糖含量和可溶性蛋白含量随着盐胁迫程度的增加表现出先升高后降低的趋势;(4)随着盐浓度的增加和盐害时间的持续,幼苗叶片MDA含量、相对电导率和脯氨酸含量总体上呈增大趋势,并在胁迫末期达到最大值。[结论]欧洲鹅耳枥幼苗在0.1%~0.2%盐胁迫下能通过调节保护酶活性和渗透调节物质来减轻危害;而在0.3%胁迫下,幼苗自我调节能力受影响,0.4%~0.5%胁迫对其造成严重的损害,表明欧洲鹅耳枥耐盐性较弱,不宜在滨海地区生长。  相似文献   

19.
  【目的】  韭菜易于吸收和累积硝酸盐，研究营养液中添加氯化钠 (NaCl) 和降低硫含量减少韭菜硝酸盐累积的效果，并从氮代谢途径初步探讨其减少硝酸盐累积的机理。  【方法】  采用新型韭菜专用营养液架床栽培系统进行了韭菜水培试验。在营养液中添加NaCl 12 mmol/L的同时，硫浓度设定为3、2、1和0 mmol/L 4个水平，分别用NaCl+S3, NaCl+S2, NaCl+S1 和 NaCl+S0表示。韭菜生长30天后，取样分析了不同硫水平下韭菜中的硝酸盐含量及主要氮代谢途径中的氨基酸含量。  【结果】  在营养液硫供应水平3 mmol/L下，与营养液中不添加氯化钠处理 (CK) 相比，NaCl+S3处理的韭菜硝酸盐累积降低了32.60%，地上部干重、可溶性糖和可溶性蛋白质含量、根系活力显著增加；NaCl+S1处理的韭菜硝酸盐累积降低了53.30%，地上部干重、可溶性糖和可溶性蛋白质含量、根系活力显著增加。NaCl+S1处理较NaCl+S3处理更有利于降低硝酸盐含量。韭菜地上部的全氮含量无显著变化 (NaCl+S3处理) 或略有增加 (NaCl+S1处理)，表明添加低浓度氯化钠并未限制氮素吸收。NaCl+S3和NaCl+S1处理下，硝态氮还原活性 (硝酸还原酶NR) 和转氨活性 (谷氨酸草酰乙酸转氨酶GOT、谷氨酸丙氨酸转氨酶GPT) 增加，尤其是初级同化活性 (谷氨酰胺合成酶GS) 分别大幅增加了43.57%和71.43%。NaCl+S3和NaCl+S1处理下，丝氨酸途径的游离氨基酸代谢和天冬氨酸途径的蛋白质合成得到增强，韭菜的游离氨基酸总量基本保持不变或略有增加，而蛋白质水解氨基酸总量显著增加。  【结论】  韭菜专用营养液中添加NaCl 12 mmol/L并将硫浓度降低到1 mmol/L，可显著提高根系和氮代谢关键酶活性，在一定程度上改变游离氨基酸代谢途径和蛋白质合成途径，进而在显著增加韭菜干物质的同时，大大降低硝酸盐累积。  相似文献   

20.
Moniliformin is a mycotoxin produced by Fusarium subglutinans and other Fusarium species. A rapid, liquid chromatographic method for its determination in corn and wheat is described. Samples are extracted in acetonitrile-water (95 + 5); following defatting with n-hexane, an aliquot of the extract is evaporated and cleaned up on small C18 and neutral alumina columns successively. Reverse-phase liquid chromatography (LC) is conducted on a C18 column with 10 or 15% methanol or acetonitrile in aqueous ion-pair reagent as mobile phase, with detection by ultraviolet absorption at 229 and 254 nm. Average recoveries of moniliformin (potassium salt) added to ground corn and wheat at levels of 0.05-1.0 micrograms/g were 80% (n = 20) and 85% (n = 12), respectively, and the limit of detection was ca 0.01-0.18 micrograms/g, depending on LC conditions. Analysis of 24 samples of wheat, 4 samples of rye, and 12 samples of corn showed moniliformin in only 2 corn samples (0.06 and 0.2 micrograms/g). Moniliformin was also detected in a sample of artificially damaged (slashed) corn (0.2 micrograms/g) and selected kernels of corn that were field-inoculated with F. subglutinans and F. moniliforme (50 micrograms/g and 0.5 micrograms/g, respectively). In stability studies, moniliformin (potassium salt, 1 microgram/g) in ground corn and ground wheat heated at 50, 100, and 150 degrees C for 0.5-2 h decomposed moderately, e.g., 55% remained in corn after 0.5 h at 100 degrees C.  相似文献   

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