Composition and secondary structure of proteins isolated from six different quinoa varieties from China

Due to its high nutritional value, quinoa has recently been attracting worldwide attention. The composition and secondary structure of proteins isolated from quinoa varieties from other countries have been determined, but proteins from Chinese quinoa varieties have not been described. The aim of this research was to determine the composition and secondary structure of proteins isolated from six different quinoa varieties from China. In all varieties, the protein content was 69.62–73.14%. The fat content and ash content were all less than 2%. The starch content was 20.67–23.12%. The amino acid composition and secondary structures of quinoa protein isolates (QPIs) purified from six Chinese quinoa varieties were investigated by using a combination of amino acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and Fourier transform infrared spectroscopy (FTIR). The results revealed that QPIs, with molecular weights ranging from 10.0 kDa to 50.0 kDa, were rich in essential amino acids. In addition, glutamic acid was the most abundant amino acid found in the quinoa protein isolates. The remaining amino acid contents were balanced, except for tryptophan. The secondary structures of QPIs have been quantified by the deconvolution of the amide I band of the FTIR spectrum of QPIs. The main secondary structure in quinoa isolate protein was the β-sheet (from 30.86% to 36.88%). These results will be promising guides for the use of QPIs in food processing and additives.     

Composition and Functional Properties of <Emphasis Type="Italic">Lupinus campestris</Emphasis> Protein Isolates

Protein isolates from L. campestris and soybean seeds were prepared using isoelectric precipitation (PI) and micellization (MI) procedures. The amount of protein recovered was considerably higher with the isoelectric precipitation than with the micellization procedure (60% and 30%, respectively). Protein contents were higher than 90% in protein isolates. Antinutritional factors content (alkaloids, lectins, and tannins) were reduced to innocuous levels after protein isolate preparation. Minimum protein solubility for the precipitated lupin protein isolate (LPI) was at pH 4.0, and between pH 4 and 6 for the micellized lupin protein isolate (LMI), increasing at both extremes of the pH scale. Water absorption for the LMI was 1.3 ml/g of protein and its oil absorption 2.2 ml/g of protein. The LPI had 1.7 ml/g of protein in both water and oil absorption. Foaming capacity and stability was pH-dependent. Foaming capacity was higher at pH 2 and lower near the protein isoelectric points. Minimum protein concentration for gelation in LMI was 8% w/v at pH 4, while for LPI was 6% at pH 4 and 6. Amino acid composition in L. campestris flour and protein isolates was high in lysine and low in methionine. Most of the essential amino acids in lupin protein isolates were at acceptable levels compared to a reference pattern for infants and adults. The electrophoretic pattern of both protein isolates showed three bands with different mobilities, suggesting that the protein fractions belong to alpha-conglutin (11S-like protein), beta-conglutin (7S-like protein) and gamma-conglutin. It is proven that some of the functional properties of L. campestris protein isolates are similar to those soybean protein isolates recovered under equal conditions.     

Potato virus X isolates from potato collected in eastern Canada with different symptoms in tobacco differ in their coat proteins

Three Canadian isolates of potato virus X (PVX) that produced distinctly different symptoms in tobacco (Nicotiana tabacum cv. Samsun) were analyzed for differences in their coat proteins using SDS-PAGE, denaturing isoelectric focusing, peptide analysis and nucleotide sequencing. The amino acid sequence of the coat protein in a mild isolate differed from that of isolates that produced severe or intermediate symptoms at two locations. However, the amino acid sequences of the Canadian isolates that produced severe or intermediate symptoms were identical and were the same as the coat proteins of PVX isolates from Argentina, China, The Netherlands, and United Kingdom. These results suggest that regions of the PVX genome in addition to the coat protein gene may be involved in viral-host interactions.     

Composition and functional properties of protein isolates obtained from commercial legumes grown in northern Spain

Pea (Pisum sativum), faba bean (Vicia faba) and soybean (Glycine max) seeds were characterized, and protein isolates were prepared following an isoelectric point precipitation procedure. Soybean seeds showed the highest protein content (36.7%) and carbohydrate was the major constituent in the pea (59.4%) and the faba bean seeds (52.1%). Protein contents were higher than 80% in all the protein isolates. The amino acid contents in the protein isolates were, in general, higher than those in their own starting seeds. The antinutritional factor contents were reduced after the protein isolate preparation. The highest reductions achieved for tannins were 95% in the faba bean protein isolate, and for phytates (45%) and trypsin inhibitor activity (46%) in the pea protein isolate. Haemagglutinating activity was not detected in any of the protein isolates. Minimum solubility values were observed at a pH range between 4.0 and 6.0, and maximal solubilities were obtained at basic pH values. The faba bean protein isolate showed the highest water and oil absorption capacities, and the best gelling properties. The soybean protein isolate had the best foam expansion capacity. Thus, the protein isolates had an improvement in some of the characteristics compared to their original seeds with lower contents in tannins, phytates and haemagglutinating activity, but had weak functional properties.     

Isolation and chemical evaluation of protein from water hyacinth

Leaf protein isolate from water hyacinth (Eichornia crassipes) was prepared and the chemical composition was studied. It contained 49.6% protein, 16.0% total lipids, 26.9% total carbohydrates, 1.7% fibre and 5.8% ash. Calcium, magnesium, copper, zinc, manganese and potassium were determined. Nutritional properties of the isolate are discussed in relation to its amino acid composition and to its in vitro digestibility by proteolytic enzymes. Comparison with the FAO/WHO reference pattern showed that all of the essential amino acids were present at high levels in the leaf protein isolate. The limiting amino acid in the isolate was methionine (i.e., methionine + cystine). In vitro digestibility was highest with digestion by pepsin followed by pancreatin and lowest with digestion by pepsin alone. Digestion with pancreatin alone gave intermediate values.     

海南黄灯笼辣椒顶死病病原病毒的分离鉴定

从海南省黄灯笼辣椒顶死病株上分离纯化得到一个病毒分离物.研究结果表明,该病毒分离物能通过汁液磨擦接种侵染供试植物中的4科11种植物,可由桃蚜传播;提纯病毒粒子呈球形,直径28～30 nm,外壳蛋白分子量约为28 ku;分离物与CMV抗血清在ELISA测定中呈阳性反应;提取病毒分离物RNA,应用RT-PCR方法克隆了病毒外壳蛋白（CP）基因.CP基因675 bp,编码218个氨基酸.对CP基因序列分析表明,该病毒分离物的CP基因核苷酸序列与黄瓜花叶病毒亚组Ⅰ分离物的同源性均在92.1%以上,所推导的氨基酸序列同源性在96.3%以上,而与亚组Ⅱ分离物的核苷酸序列同源性均低于77.3%,所推导的氨基酸序列同源性均低于80.7%.据此将该病毒分离物鉴定为黄瓜花叶病毒,归属于亚组Ⅰ.     

侵染福建省甘蔗的高梁花叶病毒全长基因的分析

从福建农林大学甘蔗综合研究所培育的甘蔗品种福农95-1702中,采集表现花叶症状的甘蔗病叶,根据NCBI上已登录的甘蔗花叶病毒全长基因序列设计引物,利用RT-PCR和RACE技术进行全长基因克隆。结果表明,病毒分离物FJ10为高梁花叶病毒,全长不包括poly(A),有9 375 bp。整个基因只有一个开放读码框,编码成由3 071个氨基酸组成的多聚蛋白,FJ10含有一些与其它马铃薯Y病毒属病毒共有的氨基酸序列。序列分析结果表明,FJ10分离物与美国的分离物SrMV-H同源性最高,核苷酸序列同源性达91.2%,编码的多聚蛋白氨基酸序列同源性达96%,与来自中国浙江的甘蔗分离物核苷酸序列同源性为82%,氨基酸序列的同源性达89.6%。     

Composition and nutritional quality of pea (Pisum sativum L.), faba bean (Vicia faba L. spp. minor) and lentil (Lens culinaris Medik.) meals,protein concentrates and isolates

Pea (Pisum sativum L.), faba bean (Vicia faba L. spp. minor), and lentil (Lens culinaris Medik.) meals, protein concentrates and isolates were analyzed for proximate composition, oligosaccharides, and amino acid composition. Protein quality was evaluated using a mouse bio-assay. The concentrates contained 59.2 to 70.6% and the isolates 86.7 to 90.8% protein (N × 6.25) on moisture-free basis. Glucose, sucrose, raffinose, stachyose and verbascose were present in the highest concentrations in the protein concentrates (7.1 to 11.1%), the pea protein concentrate contained 8.7% sugars and faba bean and lentil protein concentrates 7.1% and 6.6% respectively. The protein isolates were almost free (containing less than 0.79%) of the sugars. Amino acid composition of the meals, concentrates and isolates showed, as expected, sulfur-amino acid deficiency (about two thirds of the rat requirement), which was probably largely responsible for the low protein efficiency ratios (0.75 to 1.18), and net protein ratios (0.25 to 0.73) of the three products, compared to values of 2.56 and 2.18 respectively obtained for casein. The protein digestibilities of the meals, concentrates and isolates (81 to 90%) were similar to that of casein (87%). The poor growth-promoting abilities of the meals, concentrates and isolates were possibly also due to growth-depressing factors such as tannins, trypsin inhibitors and hemagglutinins present, particularly in faba bean and lentil.     

稻麦套种对小麦花后地上部游离氨基酸含量及籽粒品质的影响

采用稻麦套种与传统条播两种栽培方式系统比较的方法,研究了稻麦套种对优质中筋小麦扬麦10号和弱筋小麦宁麦9号花后叶、茎鞘、颖壳、穗轴、籽粒游离氨基酸和蛋白质含量以及籽粒品质的影响。结果表明,稻麦套种对不同类型小麦花后地上部各器官游离氨基酸含量和籽粒蛋白质含量及其他品质指标有显著影响。与条播栽培方式相比,稻麦套种小麦花后地上部器官的游离氨基酸含量和籽粒蛋白质、湿面筋含量等主要品质指标均较低,二者差异显著。在同一栽培方式下,弱筋小麦宁麦9号各器官游离氨基酸含量显著低于中筋小麦扬麦10号。套种方式有利于弱筋小麦品质的形成,此栽培方式下宁麦9号各项品质指标均达到国家标准,但中筋小麦扬麦10号的部分品质指标下降。     

Effects of salt stress on some nitrogen fixation parameters in faba bean

The adverse effects of sea water salinity on number of nodules, nitrogen content, nitroginase activity, Chlorophyll a and b content, proline accumulation and protein pattern of faba bean plants (Vicia faba commercial cultivar Nubaria 1) were investigated. Faba bean plants were irrigated with sea water at 20, 25, 30, 40 and 50% concentrations and inoculated with rhizobial isolate ARC307 or with gamma rays treated isolates namely; ARC1, ARC2, ARC3, ARC4, ARC5, ARC6 and ARC7. Nodules number, nitrogen content, nitroginase activity and chlorophyll a and b content parameters were decreased by increasing sea water salinity with all used isolates, while proline accumulation parameter increased. At the same time, ARC2 isolate showed the highest values for these parameters above all isolates including the parental isolate ARC307 at all studied concentrations except for proline accumulation parameter, it was the least. Therefore, ARC2 considered as a promising isolate for salt tolerance. Salinity enhanced the occurrence of particular novel proteins in faba bean plants infected with ARC2 isolate.     

土壤肥力对小麦开花后各器官游离氨基酸和籽粒蛋白质含量变化的影响

能过随机区组试验和相关的方法，研究了两种土壤肥力条件下小麦开花后植株体内游离氨基酸含量的变化动态及其与籽粒蛋白质含量的关系。结果表明，开花后小麦植株各器官游离氨基酸含量均与籽粒蛋白质含量呈显著或极显著正相关，土壤肥力高能够显著提高各器官中的游离基酸含量，并延长维持高水平的时间，进而促进籽粒蛋白质合成，提高籽闰蛋白质含量和改善品质。     

Chemical composition and nutritional quality ofCleome dolichostyla seeds

Seeds ofCleome dolichostyla were analysed for proximate composition, mineral element contents and amino acid composition, in-vitro protein digestibility (IVPD) and calculated protein efficiency ratio (C-PER). The seeds (dry basis) were rich in oil (32.1%), protein (24.6%) and fiber (17.8%) content. The contents of various mineral elements mg/100 g) were: Ca=1970, P=493, Mg=127, Na=35, K=465, Fe=71.97, Zn=2.25, Cu=0.44 and Mn=1.45. Aspartic acid, glutamic acid, glycine, arginine and histidine were the major amino acids inC. dolichostyla seed protein accounting for half of the total amino acids. Lysine was the most limiting essential amino acid (FAO/WHO, 1973 reference pattern) with a chemical score of 45 for the protein. The IVPD of cleome seed protein was 72.2% and C-PER was 1.08 relative to the IVPD and C-PER values of 90.0% and 2.50 for the Animal Nutrition Research Council casein.     

Relationship between amino acid scores and protein quality indices based on rat growth

Protein efficiency ratio (PER), relative PER (RPER), net protein ratio (NPR) and relative NPR (RNPR) values, and amino acid scores were calculated for 20 food products (casein, casein + Met, beef salami, skim milk, tuna, chicken frankfurters, sausage, heated skim milk, peanut butter, rolled oats, soy isolate, chick peas, pea concentrate, kidney beans, wheat cereal, pinto bean, lentils, rice-wheat gluten cereal, macaroni-cheese, and beef stew). In most cases, PER, RPER, NPR or RNPR ranked the products in the same order and positive correlations among the protein quality methods were highly significant (r=0.98–0.99). Amino acid scores (based on the first limiting amino acid, Lys-Met-Cys, Lys-Met-Cys-Trp or lys-Met-Cys-Trp-Thr) were positively correlated to the PER, RPER, NPR or RNPR data (r=0.61–0.75). Inclusion of the correction for true digestibility of protein improved the correlations between amino acid scores and the indices based on rat growth. The correlations were especially high between Lys-Met-Cys scores (corrected for true digestibility of protein) and PER, RPER, NPR or RNPR (r=0.86–0.91). Inclusion of the correction for true digestibility of individual amino acids did not result in further improvements of the correlations in most cases. It is concluded that adjusting amino acid scores for true digestibility of protein would be sufficient and further correction for digestibility of amino acids would be unnecessary in mixed diets.This paper was presented in part at the 71st annual FASAB meeting, Washington, DC, March 29–April 2, 1987.     

蓖麻碳氮代谢规律及其 与株高关系的初步分析

对4个不同株高的蓖麻品种生育过程中可溶性糖、还原糖、蔗糖转化酶、可溶性蛋白、谷氨酰胺合成酶、 游离氨基酸的差异进行了比较研究。结果表明,株高快速增长时期在7月上旬至8月上旬;不同株高的蓖麻品种 其碳氮代谢指标存在差异,在生育前期叶片相对较多的可溶性糖积累和旺盛的氮代谢以及生育中后期高的蔗糖转 化酶活性、低还原糖含量有利于其株高的增长。     

Content and Quality of Protein in Proso Millet (Panicum miliaceum L.) Varieties

Proso millet belongs to the oldest cereals that human is using. Eight varieties of proso millet were cultivated in Ceske Budejovice from1998 to 2000 and Cerveny Dvur from 1999 to 2000. The crude protein content was determined according to Kjehladl method and amino acid content was determined chromatographically after acid and oxidative acid hydrolysis. Although the protein content of proso (11.6% of dry matter) was similar to wheat, the grain of proso was significant richer in essential amino acids (leucine, isoleucine, methionine) then wheat. Hence, the protein quality of proso (Essential Amino Acid Index) was higher (51%) compared to wheat. The proso grain contained about 3.3 g kg⁻¹ of the limiting amino acid-lysine. Significant differences in protein and its quality were found among the evaluated proso varieties. The varieties Toldanskoe and Lipetskoe were the most different from the others in protein and amino acid content and Amino Acid Score of individual acids. They had the lowest content and quality of protein. The seed coat of these varieties was red. The amino acid and protein content was significantly influenced by weather during the year. Dry conditions caused an increase of protein but its quality was decreased.     

侵染玉米的甘蔗花叶病毒HC-Pro基因的克隆与表达

采用RT-PCR方法从郑州地区感染甘蔗花叶病毒(Sugarcane mosaic virus,SCMV)的玉米叶片中克隆病毒编码的辅助成分-蛋白酶基因(Helper component proteinase,HC-Pro),基因大小1380bp,编码460个氨基酸。序列比对和系统进化树分析表明,HC-Pro编码的氨基酸序列与北京、山东、河南、陕西、浙江、广东、西班牙、保加利亚和墨西哥等地的SCMV分离物中的氨基酸序列相似性在82%～92%,表明分离的SCMV可能是一个新的病毒分离物。利用半定量RT-PCR分析了HC-Pro在接种SCMV玉米自交系后的表达和积累的动态变化,结果表明,接种7d后,HC-Pro在心叶中积累到相当高的程度,9d后达到高峰,说明HC-Pro可能参与了SCMV在玉米植株中的系统侵染过程。     

椰麸组分蛋白的氨基酸组成、结构与乳化性分析

为提高椰子加工副产物的利用,本研究从椰麸中依次提取4种组分蛋白,包括清蛋白、球蛋白、谷蛋白-1和谷蛋白-2.分析这4种组分蛋白的氨基酸组成,并利用SDS-PAGE技术分析其亚基组成和分子量.同时分析其表面疏水性,并研究不同离子强度对椰麸各组分蛋白的乳化性和乳化稳定性的影响.结果表明,椰麸蛋白质中清单白、球蛋白、谷蛋白-...     

Dry heat popping of amaranth seed might damage some of its essential amino acids

Amaranth was a major crop among the Aztecs. In Mexico the seed is popped and eaten with brown sugar. The crude protein content of the seed is 14±2% but its contents of lysine and tryptophan are 6.2 and 1.6 g/16 g N respectively. We developed a popping method based on a fluid bed system (FBS) whereas the traditional method (TM) is just to pop the seeds manually in a hot plate. Assays carried out were evaluation of racemization of the amaranth protein due to heat treatment, amino acid composition of the raw and heat treated seeds and a biological experiment testing whether leucine was the most limiting amino acid of amaranth protein. Male rats were fed both popped amaranths and roasted amaranth. Parboiled amaranth and casein were controls. The results were: (a) Lys, Arg and Cys were damaged in the heat treated seeds; (b) Asp, Met, Glu, Ala and Phe were racemized in that decreasing order in the seeds popped and roasted by the TM; (c) the estimated net protein retention (NPR) and estimated net protein utilization (NPU) of popped amaranths by either method were not different, but were lower than for the parboiled amaranth. The parboiled amaranth was not different from casein; (d) Leu was not the most limiting amino acid in any of the amaranth seeds tested. After Lys, sulfur amino acids appear to be the next most limiting in severely heat treated amaranth. The FBS seems to be a promising method for popping amaranth at industrial level.     

Effect of sesame seed proteins supplementation on the nutritional,physical, chemical and sensory properties of wheat flour bread

Sesame products (sesame meal, roasted and autoclaved sesame meal, sesame protein isolate and concentrate) were added to Red wheat flour to produce blends at protein levels of 14, 16, 18 and 20 percent. Dough properties were studied using a Brabender Farinograph. Loaves were prepared from the various blends using the straight dough procedure and then evaluated for volume, crust and crumb colour, crumb texture, flavour and overall quality. The water absorption, development time and dough weakening were increased (p<0.05) as the protein level increased in all blends; however, dough stability decreased. Sesame products could be added to wheat flour up to 18 percent protein level (sesame protein isolate) and up to 16 percent protein level (other sesame products) without any observed detrimental effect on bread sensory properties. No significant differences (p>0.05) were recorded in loaf volume between control and breads containing sesame protein isolate (up to 18 percent protein level) and either autoclaved sesame meal or sesame protein concentrate (up to 14 percent protein level). Addition of sesame products increased the content not only of protein but also minerals and total essential amino acids, especially lysine. The addition also improved in-vitro protein digestibility.     

Protein Digestibility using Corrected Amino Acid Score method (PDCAAS) of four types of mushrooms grown in Jordan

This study was conducted to evaluate the protein quality of four types ofedible mushrooms common in Jordan in terms of protein digestibility –corrected amino acid score (PDCAAS), which is a combination of thechemical score of the limiting amino acid multiplied by true digestibility ofthe protein. True protein digestibility values were low (61.4, 73.4, 52.6and 80.5 for Terfezia claveryi, Pleurotus ostreatus, Tricholoma terrum and Agaricus macrosporus, respectively). Based onthe essential amino acids pattern requirements for children, the limitingamino acids in P. ostreatus and A. macrosporus protein weresulphur-containing amino acids with chemical scores of 0.61 and 0.50,respectively. However, lysine was the limiting amino acid in the protein ofT. claveryi and T. terreum with chemical scores of 0.71 and 0.67,respectively, and the PDCAAS was 0.43, 0.45, 0.35 and 0.40 for themushrooms types, respectively. Considering the pattern of essential amino acid requirements of laboratory rats, thesulphur containing amino acids were the limiting amino acids in the proteinof T. claveryi, P. ostreatus, T. terreum and A.macrosporus with chemical scores of 0.56, 0.30, 0.34 and 0.25,respectively. The PDCAAS were 0.34, 0.22, 0.17 and 0.20,respectively. It is concluded that the four mushroom types studied are of lowprotein quality.