Trypsin isoinhibitors of lucerne: Association with leaf fraction 1 protein

Trypsin inhibitory activity occurring in the vegetative portion of lucerne (Medicago sativa L.) comprised two heat-labile isoinhibitors with isoele     

30种植物叶蛋白中氨基酸组成及含量的测定与营养价值评价

评价植物叶蛋白的营养价值,既要考虑“量”,看植物叶蛋白含量的高低,也要考虑“质”,看必需氨基酸的含量及配比[1]。作者取叶蛋白含量50%以上的30种植物进行氨基酸含量测定[2],并进行营养价值评价。1　方　　法应用日立83550型氨基酸自动分析仪进行氨基酸含量的测定,并与?..     

植物叶蛋白提取方法的比较

随着畜牧业的迅速发展,蛋白质饲料供应严重不足的问题日益突出。世界各国都在积极寻求开发利用蛋白质饲料资源［１］。其中开发利用植物叶蛋白是一条有效的途径［２］。我国有高等植物３００００余种,可作饲料的有２０００余种［３］,山东省有高等植物近２４００种,可...     

Relationships between the osmoadaptation strategy, amino acid composition of bulk protein, and properties of certain enzymes of haloalkaliphilic bacteria

Haloalkaliphilic microorganisms isolated from soda lakes were compared in terms of the amino acid composition of bulk protein and the reaction of a number of key enzymes to salts and pH of the medium. In the extremely haloalkaliphilic bacterium Natroniella acetigena (selt-in osmoadaptation strategy), acidic amino acids (glutamic and aspartic) made up 30.91 mol % of the total of bulk protein amino acids. In the moderate haloalkaliphiles Tindallia magadiensis, Halomonas campisalis, and Halomonas sp. AIR-2 (compatible-solutes osmoadaptation strategy), the proportion of acidic amino acids (24.36, 23.15, and 23.58 mol %, respectively) was lower than in N. acetigena but higher than in the freshwater Acetobacterium paludosum (20.77 mol %). The excess of acidic amino acids over basic amino acids (lysine and arginine) increased with the degree of halophily. The enzymes of haloalkaliphiles proved to be tolerant to salts and high pH values, although the degree of tolerance varied. The activity of N. acetigena CO dehydrogenase was maximum in the presence of 0.7 M NaCl, but it was virtually independent of the NaHCO₃ concentration. The hydrogenase and CO dehydrogenase of T. magadiensis exhibited maximum activity in the absence of NaCl; the Co dehydrogenase was most active at 0.25 M NaHCO₃, and hydrogenase activity was only weakly dependent on NaHCO₃ in the concentration range of 0–1.2 M. The nitrate reductases of H. campisalis and Halomonas sp. AIR-2 were active in broad ranges of NaCl and KCl concentrations; the activity maxima were recorded at moderate concentrations of these salts. The pH optima of most of the studied enzymes of haloalkaliphiles were in the alkaline zone. Thus, it was shown that the amino acid composition of bulk protein is determined by the osmoadaptation strategy employed by the bacterium. A correlation was found between the salt tolerance of enzymes and the proportion of acidic amino acids in the bulk protein. The ability of enzymes to function at high pH values is one of the mechanisms of adaptation of microorganisms to high pH values.     

The STENOFOLIA gene from Medicago alters leaf width,flowering time and chlorophyll content in transgenic wheat

Molecular genetic analyses revealed that the WUSCHEL‐related homeobox (WOX) gene superfamily regulates several programs in plant development. Many different mechanisms are reported to underlie these alterations. The WOX family member STENOFOLIA (STF) is involved in leaf expansion in the eudicot Medicago truncutula. Here, we report that when this gene was ectopically expressed in a locally adapted hard red winter wheat cultivar (Triticum aestivum), the transgenic plants showed not only widened leaves but also accelerated flowering and increased chlorophyll content. These desirable traits were stably inherited in the progeny plants. STF binds to wheat genes that have the (GA)_n/(CT)_n DNA cis element, regardless of sequences flanking the DNA repeats, suggesting a mechanism for its pleiotropic effects. However, the amino acids between position 91 and 262 in the STF protein that were found to bind with the (GA)_n motif have no conserved domain with any other GAGA‐binding proteins in animals or plants. We also found that STF interacted with a variety of proteins in wheat in yeast 2 hybrid assays. We conclude that the eudicot STF gene binds to (GA)_n/(CT)_n DNA elements and can be used to regulate leaf width, flowering time and chlorophyll content in monocot wheat.     

Sorting of precursor proteins between isolated spinach leaf mitochondria and chloroplasts

The precursors of the F₁-ATPase -subunits fromNicotiana plumbaginifolia andNeurospora crassa were imported into isolated spinach (Spinacia oleracea L.) leaf mitochondria. Both F₁ precursors were imported and processed to mature size products. No import of the mitochondrial precursor proteins into isolated intact spinach chloroplasts was seen. Moreover, the precursor of the 33 kDa protein of photosynthetic water-splitting enzyme was not imported into the leaf mitochondria. This study provides the first experimental report ofin vitro import of precursor proteins into plant mitochondria isolated from photosynthetic tissue and enables studies of protein sorting between mitochondria and chloroplasts in a system which is homologous with respect to organelles. The results suggest a high organellar specificity in the plant cell for the cytoplasmically synthesized precursor proteins.     

4种小檗科植物叶片的蛋白质及氨基酸组成分析

蛋白质和氨基酸是植物体内重要的营养物质,研究药用植物的蛋白质和氨基酸组成对药用植物资源的合理开发和综合利用具有重要意义,但目前对药用植物次生代谢物的研究较为广泛（如黄酮类化合物[1-2],而对其初生代谢物的研究相对较少[3-4]。     

Varietal differences of leaf protein profiles in mulberry

Varietal differences in the leaf protein profiles of 17 diploid (2n = 28) varieties of mulberry (Morus spp.) were demonstrated by 2D-gel electrophoresis and silver staining; similarity was statistically evaluated by means of principal component analysis. A close correlation was found between inter-varietal similarity, as estimated by the electrophoretic banding patterns of certain enzymes, and the leaf protein profiles obtained by 2D-gel electrophoresis. Little apparent varietal difference in the amount of ribulose-1,5-bisphosphate carboxylase was detected immunoelectrophoretically in the leaves. Varietal differences in crude protein content were obtained with leaves and this was discussed in relation to the observed 2D-gel electrophoretic patterns.     

Structure of acacigenin-B,a novel triterpene ester isolated from Acacia concinna

The structure of acacigenin-B, a novel ester genin from the pods of Acacia concinna was established from its PMR and ¹³ C NMR spectra. It was identified as the 21-hydroxy ester of acacic acid; the esterifying acid was a hitherto unknown monoterpene acid of tetrahydrofuranoid structure. This appears to be the first report of a higher terpenoid forming an ester with a monoterpene acid     

Inhibitory effects of Hymenaea and Copaifera leaf resins on the leaf fungus, Pestalotia subcuticularis

Leaf resins in the leguminous genera Hymenaea and Copaifera may play a role in restricting infection by the associated leaf fungus, Pestalotia. We tested this hypothesis by assessing growth of the geographically widespread Pestalotia subcuticularis presented with different compositions of resins. Leaf resins of Hymenaea and Copaifera are composed of the same suite of sesquiterpene hydrocarbons, but these vary quantitatively to form discrete compositional patterns among individuals and populations. Leaf resins may also contain sesquiterpene oxides; caryophyllene oxide, which may have been formed from the caryophyllene precursor common in these resins, inhibited fungal growth in vitro.     

The antimicrobial properties of milkfat after partial hydrolysis by calf pregastric lipase

Studies on the kinetic characteristics of calf pregastric lipase (EC 3.1.1.3) have shown that it preferentially releases short chain fatty acids (SCFAs) from bovine milkfat. The released fatty acids form mixed micelle structures. The aim of this investigation has been to test whether hydrolysed milkfat is antimicrobial, and how the state of the emulsion alters the bactericidal or bacteriostatic effects. Partial hydrolysis of milkfat by pregastric lipase was carried out in two types of emulsion systems, containing either Triton X-100 or casein/lecithin, plus milkfat in citrate/phosphate buffer (pH 5.0-6.0). The concentrations and compositions of fatty acids were determined by gas chromatography. The minimum percentages of hydrolysed milkfat which affected growth and survival of selected Gram-positive and Gram-negative bacteria were measured. The bacterial experiments were repeated using pure fatty acids at similar concentrations. Lauric acid (C12:0) was found to be the most potent bactericidal fatty acid against Enterococcae (Gram-positive), and caprylic acid (C8:0) was the most potent against coliforms (Gram-negative). Use of Triton X-100 for milkfat emulsification provided a more compatible medium for studying bacterial growth in the hydrolysed milkfat than did use of casein/lecithin. The results also show that the antimicrobial effects of individual fatty acids released from hydrolysed milkfat were at least additive and suggest that hydrolysis of milkfat may be a significant factor in controlling growth of organisms imbibed with food in pre-weaned animals. The amount of pregastric catalyzed triglyceride hydrolysis in the digestive tract is sufficient to produce an antibacterial concentration of fatty acids and monoglycerides.     

Economic comparison of multiple techniques for recovering leaf protein in biomass processing

Leaf protein concentrates (LPC) can be used as a valuable co-product to cellulosic biofuel production and can also mitigate the food versus fuel controversy. Two major approaches have been considered for LPC production: a well-characterized mechanical pressing method and a less studied method involving aqueous extraction with recovery using ultrafiltration. Experimental results with switchgrass extracts show low protein recovery after filtration, particularly if protein is recovered after cellulose hydrolysis. Economic modeling suggests that aqueous extraction costs less than mechanical pressing, but due to lower protein yields and lower quality, overall profit is higher for mechanical pressing versus aqueous extraction ($26/Mg feedstock vs. $14/Mg). If modest improvements can be made in extraction yields, filtration recovery, and protein quality, then the profitability of the aqueous extraction approach can be increased to $37/Mg feedstock. This study suggests that aqueous extraction is a viable alternative for LPC co-production in a biorefinery if key improvements can be made in the process.     

The importance of inhibiting polyphenol oxidase in the extraction of fraction 1 leaf protein

The interaction between polyphenol oxidation products and Fraction 1 protein produces a modified protein of increased electrophoretic mobility. A method is described for the extraction of red clover leaf Fraction 1 protein free of polyphenol oxidation products by inhibiting polyphenol oxidase with sodium diethyldithiocarbamate.     

DNA-induced partial unfolding of prion protein leads to its polymerisation to amyloid

The full-length mouse recombinant prion protein (23-231 amino acid residues) contains all of its structural elements viz. three alpha-helices and a short two-stranded antiparallel beta-sheet in its C-terminal fragment comprising 121-231 amino acid residues. The incubated mixture of this prion protein fragment and nucleic acid results in the formation of amyloid fibres evidenced from electron microscopy, birefringence and fluorescence of the fibre bound Congo Red and Thioflavin T dyes, respectively. The secondary structure of the amyloid formed in nucleic acid solution is similar to the in vivo isolated prion protein 27-30 amyloid but unlike in it, a hydrophobic milieu is absent in the 121-231 amyloid. Thermal denaturation study demonstrates a partial unfolding of the protein fragment in nucleic acid solution. We propose that nucleic acid catalyses unfolding of prion protein helix 1 followed by a nucleation-dependent polymerisation of the protein to amyloid.     

Efficient release of ferulic acid from sweet potato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>) stems by chemical hydrolysis

An efficient method for release of ferulic acid from sweet potato stems was developed. Ferulic acid along with phenolic compounds were released from stems by acid and alkaline treatments. The base hydrolysis with 0.1 N NaOH yielded the highest quantity of total extracts (471.1 mg/g). The stems released more phenolic compounds when 0.0125∼0.025 N NaOH was employed. Where as ferulic acid release was maximal with 0.05 N H₂SO₄ (0.32 mg/g). Ferulic acid was separated from phenolics by column chromatography. Among the elution solvents, ethyl acetate fractions (80%) contained ferulic acid. Ethyl acetate eluants were further fractionated with n-hexane/ethyl acetate/formic acid (100/50/0.5, v/v/v). All fractions showed ferulic acid and phenolic compounds. Fraction V among them was ascribed to ferulic acid with an yield of 5.41 mg/g of dry sweet potato tissue.     

Inhibition of protein synthesis by products of lipid peroxidation

Effects of lipid peroxidation products on in vivo and in vitro protein synthesis have been studied. Malondialdehyde (MDA), a product, and a routinely used index of lipid peroxidation, inhibits in vivo protein synthesis in the two mosses, Tortula ruralis and Cratoneuron filicinum, and in pea (Pisum sativum) leaf discs. When wheat germ supernatant or poly(A)-rich mRNA of T. ruralis was incubated with MDA its subsequent activity in a cell-free protein-synthesizing system was reduced. When MDA was added directly to the in vitro protein-synthesizing mixture containing moss polyribosomes, the inhibition of amino acid incorporation was small. However, when simultaneous lipid peroxidation was allowed to occur along with in vitro protein synthesis there was a strong inhibition of amino acid incorporation and MDA accumulated in the reaction mixture indicating that products of lipid peroxidation other than, and apparently more toxic than, MDA were involved. It was concluded that lipid peroxidation inhibits protein synthesis probably by releasing toxic products which may react with and inactivate some components of the protein-synthesizing complex.     

阿魏酸酯酶A的基因克隆与表达及其水解产物的纯化

为在毕赤酵母中表达来源于米曲霉Aspergillus oryzae的A型阿魏酸酯酶并研究其水解功能,探讨大孔树脂对其水解产物阿魏酸的纯化条件及纯化效果,以米曲霉A.oryzae CICC 40186总RNA为模板,通过RT-PCR技术克隆出了米曲霉阿魏酸酯酶A(AorFaeA)成熟肽的编码基因AorfaeA,并借助pPIC9K质粒实现了其在毕赤酵母GS115中的异源表达。SDS-PAGE分析结果显示纯化后的重组阿魏酸酯酶(reAorFaeA)为单一条带,其表观分子质量约39.0 kDa。以阿魏酸甲酯为底物,经高效液相色谱法测得该酶的最高酶活为58.35 U/mg。利用reAorFaeA和木聚糖酶复合酶水解去淀粉麦麸制备阿魏酸,用大孔树脂纯化小麦麸皮阿魏酸粗提液,所测树脂中HPD-300型大孔树脂的吸附量和解吸率较高,以50%的乙醇为洗脱液,当流速为1.0 mL/min时洗脱效果较好。在该纯化条件下,阿魏酸的回收率为92%,质量分数由原材料中的0.13%富集提高到10.55%。这些研究为阿魏酸的酶法"绿色生产"及应用奠定了坚实的理论基础。     

Detection of sugarcane yellow leaf virus,the causal agent of yellow leaf syndrome in sugarcane by DAS-ELISA

DAS-ELISA studies were conducted on detection of sugarcane yellow leaf virus (SCYLV) causing yellow leaf syndrome (YLS) of sugarcane in leaf and juice antigens. Among the two types of antigen sources used for the virus detection, juice antigen showed high titre for the virus as compared to leaf antigen. Assay with juice samples recorded more number of varieties positive to the virus. Further DAS-ELISA studies revealed that plants raised from disease-infected planting materials recorded high titre for SCYLV as compared to those raised from symptom-free seed canes. Similarly, assaying SCYLV titre in plant and ratoon crop in the field showed that SCYLV infection was partial in plant crop and in the subsequent ratoon crop, all the samples were positive to the virus. ELISA studies also indicated that 33 of 41 cane varieties showing YLS were positive to the virus.     

The early light-induced protein is also produced during leaf senescence of Nicotiana tabacum

To better understand the genetic controls of leaf senescence, a tobacco (Nicotiana tabacum L. cv. SR1) mRNA that is up-regulated during senescence was isolated by the cDNA-amplified restriction fragment polymorphism method and the cDNA was cloned. The mRNA coded for the early light-induced protein (ELIP), a member of the chlorophyll a/b-binding protein family that has been implicated in assembly or repair of the photosynthetic machinery during early chloroplast development and abiotic stress. A protein antigenically recognized by antibodies to ELIP appeared during senescence with kinetics similar to those of its mRNA. The mRNA, designated ELIP-TOB, was detected earlier when senescence was enhanced by leaf detachment and treatment with 1-amino-cyclopropane-1-carboxylic acid, and was detected later when senescence was retarded by benzyladenine. However, no ELIP-TOB mRNA was seen in the dark even though senescence was accelerated under these conditions. Furthermore, water stress and anaerobiosis stimulated the appearance of ELIP-TOB mRNA before losses of chlorophyll could be detected. We discuss the conditions that may lead to the up-regulation of ELIP-TOB during senescence and speculate as to the role of the gene product in this terminal phase of leaf development. Received: 18 May 2000 / Accepted: 24 June 2000     

Enhancement of leaf nitrogen,phosphorus and potassium and seed protein in Vigna radiata by pyridoxine application

Soaking the seeds of mungbean (Vigna radiata L. Wilczek cv. K-851) in pyridoxine solution significantly enhanced leaf N, P and K concentrations at different growth stages, and seed protein concentration at harvest. Leaf N, P and K were significantly correlated with root length and seed protein. Thus, pyridoxine application not only enhanced the availability of nutrients to plants but also was responsible for the maintenance of a favourable source-sink relationship, thus ensuring more nutritious seeds of mungbean.