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Summary The seasonal changes in the pattern of 21 amino acids occurring in the xylem vessels of Populus twigs have been studied in connection to the mobilization of protein bodies in ray parenchyma cells at the electron microscopic level. Hydrolysis of protein bodies in spring and movement of amino acids into vessels are found to be closely linked. Comprising more than 75% of total amino acid content, glutamine (Gln) is by far the dominant N-constituent of the sap. Gln reaches up to 11 mol ml-1 in the spring sap while other amino acids only show 1/20 to 1/100 of this amount. From the measured Gln accumulation rates in the vessels in nature and in the vessels of isolated shoots, a minimum flux rate for Gln of 5.6 pmol cm-2 min-1 is calculated for the ray contact cell/vessel interface. Furthermore, because Gln constitutes 75% of the amino acid content of the sap but only 1.3% of the amino acids in the 32 kDa storage protein of the ray cells in the wood (Clausen and Apel 1991), it becomes evident that most amino acids originating from protein body mobilization do not enter the vessels but are used for Gln synthesis preceding Gln release into the vessels. 相似文献
3.
Busquets M Deroncelé V Vidal-Mas J Rodríguez E Guerrero A Manresa A 《Antonie van Leeuwenhoek》2004,85(2):129-139
The isolation of a new lipoxygenase-like (LOX-like) enzyme from Pseudomonas 42A2 and its characterization is described. The enzyme, located in the periplasm of the cell, which contained 0.55 mol of Fe2+ per mol of protein, is monomeric and has a molecular mass of 45 kDa. In the presence of oxygen, the enzyme converts oleic acid into (E)-10-hydroperoxy-8-octadecenoic acid (HPOD), which decomposes to the corresponding (E)-10-hydroxy-8-octadecenoic acid (HOD). The absolute configuration of this acid was determined as S on the basis of exciton-coupled CD data, and specific rotation and NMR analysis of the corresponding p -bromobenzoate derivative. The reaction in vivo leads to the dihydroxy derivative (E)-7,10-dihydroxy-8-octadecenoic acid (DHOD), so that the three hydroxy-fatty acids can be isolated from the culture medium. The activity of the enzyme was optimal between 25 and 30 degrees C and 44% of its activity still remained at 55 degrees C. Its optimal pH is 8.5-9; and the presence of magnesium ions increased LOX activity by 1.5. The activity of the LOX is highest in unsaturated fatty acids containing double bonds in position 9 (oleic, linoleic and linolenic acids), linoleic acid being preferred (100% activity) over linolenic (60.4%) and oleic acids (46%). However, kinetic studies showed that the affinity of the enzyme is similar for the three substrates. 相似文献
4.
Desulfovibrio vietnamensis 《Anaerobe》1996,2(6):385-392
From samples collected in crude oil storage tanks and oil production waters near the coastal town of Vung Tau in Southern Vietnam, several strains of sulfate-reducing bacteria were isolated and maintained in pure culture. Strain G3 100 consisted of vibrio-shaped, motile, non-sporulating, Gram-negative, desulfoviridin-containing cells. It grew optimally at 5% NaCl. It utilized a range of organic acids as electron donors in the presence of sulfate, including lactate, malate, formate and fumarate. Ethanol and glycerol were also used. In the presence of lactate, thiosulfate, sulfite, sulfate and fumarate were used as electron acceptors. Organic substrates were not fermented. The DNA base composition of G3 100 was 60·6 mol % G + C. On the basis of 16S rRNA sequence data, G3 100 should be included in the genusDesulfovibrio. However, its physiology, whole-cell protein pattern and susceptibility to antibiotics were different from other members of this genus. Therefore, G3 100 should be recognized as a new species, for which we propose the nameDesulfovibrio vietnamensis. 相似文献
5.
高温蛋白酶制备酶解猪血蛋白的研究 总被引:16,自引:1,他引:15
杨炜 《氨基酸和生物资源》1996,18(2):1-4
用高温蛋白酶WF146制备猪血水解蛋白得率在10%(W/V)以上。水解液经分析含有18种氨基酸,其中8种必需氨基酸占37.14%。氨基酸总量可达6264.86mg/100ml.产物具有较高的营养价值和良好的溶解性,因而在食品工业中具有很大的应用潜力。 相似文献
6.
After crude protein of the marine yeast strains maintained in this laboratory was estimated by the method of Kjehldahl, we
found that the G7a strain which was identified to be a strain of Cryptococcus aureus according to the routine identification and molecular methods contained high level of protein and could grow on a wide range
of carbon sources. The optimal medium for single-cell protein production was seawater containing 6.0 g of wet weight of Jerusalem
artichoke extract per 100 ml of medium and 4.0 g of the hydrolysate of soybean meal per 100 ml of medium, while the optimal
conditions for single-cell protein production were pH 5.0 and 28.0°C. After fermentation for 56 h, 10.1 g of cell dry weight
per liter of medium and 53.0 g of crude protein per 100 g of cell dry weight (5.4 g/l of medium) were achieved, leaving 0.05 g
of reducing sugar per 100 ml of medium and 0.072 g of total sugar per 100 ml of medium total sugar in the fermented medium.
The yeast strain only contained 2.1 g of nucleic acid per 100 g of cell dry weight, but its cells contained a large amount
of C16:0 (19.0%), C18:0 (46.3%), and C18:1 (33.3%) fatty acids and had a large amount of essential amino acids, especially lysine (12.6%) and leucine (9.1%), and vitamin
C (2.2 mg per 100 g of cell dry weight). These results show that the new marine yeast strain was suitable for single-cell
protein production. 相似文献
7.
A cry1Ab-type gene was cloned from a new isolate of Bacillus thuringiensis by PCR. When restriction pattern was compared with that of known genes it was found to have additional restriction site for ClaI. Nucleotide sequencing and homology search revealed that the toxin shared 95% homology with the known Cry1Ab proteins as compared to more than 98% homology among the other reported Cry1Ab toxins. The gene encoded a sequence of 1,177 amino acids compared to 1,155 amino acids encoded by all the other 16 cry1Ab genes reported so far. An additional stretch of 22 amino acids after the amino acid G793 in the new toxin sequence showed 100% homology with several other cry genes within cry1 family. Homology search indicated that the new cry1Ab-type gene might have resulted by nucleotide rearrangement between cry1Ab and cry1Aa/cry1Ac genes. 相似文献
8.
A mixed culture containing two recombinant Bacillus subtilis strains; was used to hydrolyze 1% chicken feather; both were previously transformed with late-expressed and early expressed
alkaline protease (aprE) carrying plasmids pS1 and p5.2, respectively. Proteolytic and keratinolytic activities of the mixed culture increased in
parallel with those of the culture of B. subtilis DB100 (p5.2), and both were higher than that of B. subtilis (pS1) cultures. On the other hand, data indicated that degradation of feather by the recombinant strains B. subtilis DB100 (p5.2), was greatly enhanced when using a previously optimized medium. High levels of free amino groups as well as
soluble proteins were also obtained. The concentration of amino acids was considerably increased during the fermentation process.
It was found that, the amino acids Phe, Gly and Tyr were the major amino acids liberated in the cultures initiated by both
strains. Results render these recombinant strains suitable for application in feather biodegradation large scale processes. 相似文献
9.
A cDNA encoding the mature, chloroplast-localized carbonic anhydrase in pea has been expressed inE. coli. The enzyme is fully active and yields of up to 20% of the total soluble protein can be obtained from the bacteria. This expression system was used to monitor the effects of site-directed mutagenesis of seven residues found within conserved regions in the pea carbonic anhydrase amino acid sequence. The effects of these modifications are discussed with respect to the potential of various amino acids to act as sites for zinc coordination or intramolecular proton shuttles. 相似文献
10.
Microalgae aquaculture feeds 总被引:6,自引:0,他引:6
John R. Benemann 《Journal of applied phycology》1992,4(3):233-245
Microalgae feeds are currently used in relatively small amounts in aquaculture, mainly for the production of larvae and juvenile shell- and finfish, as well as for raising the zooplankton required for feeding of juvenile animals. The blue-green algaSpirulina is used in substantial amounts (over 100 t y–1) as a fish and shrimp feed, and even larger markets can be projected if production costs could be reduced. Another potential large-scale application of microalgae is the cultivation ofHaematococcus for the production of the carotenoid astaxanthin, which gives salmon flesh its reddish color. In the long-term microalgae biomass high in lipids (omega-3 fatty acids) may be developed as substitutes for fish oil-based aquaculture feeds. In shrimp ponds the indigenous algal blooms supply a part of the dietary requirements of the animals, but it is difficult to maximize algal productivities. A separate algal production system could feed the shrimps and minimize the need for added feed. Bivalves feed essentially exclusively on marine microalgae throughout their life cycle. The development of cultivation technologies for such microalgae would allow the onshore production of these animals, with greatly improved product quality and safety.This paper was presented at the Symposium on Applied Phycology at the Fourth International Phycological Congress, Duke University. 相似文献
11.
High-cell-density cultivation of Schizochytrium sp. in an ammonium/pH-auxostat fed-batch system 总被引:1,自引:0,他引:1
Thraustochytrids, in particular Schizochytrium spp., are used for the production of the valuable polyunsaturated fatty acid, docosahexaenoic acid (DHA; 22:6 n-3). Growth of Schizochytrium sp. G13/2S in a defined medium was initially made in shake-flask cultures to determine the optimum concentrations of glucose (100-200 g l(-1)) and ammonia ( approximately 300 mg l(-1)) that could be used by this microorganism. In subsequent fermenter cultures, a pH-auxostat method was used to maintain NH(3) from 200-300 mg l(-1). During the first 49 h of fermentation, 150 g glucose l(-1) produced 63 g cell dry wt l(-1). Although growth was not limited by the supply of nitrogen, total fatty acids were at 25% cell dry wt which is more than half the final lipid content of commercially-grown Schizochytrium biomass which uses N-limited medium in the final stages for maximum lipid accumulation. This strategy is therefore useful for the cultivation of Schizochytrium to a high cell density up to the point when lipid accumulation can be triggered by N exhaustion. 相似文献
12.
Studies on enzymatic hydrolysis of cell proteins in green microalgae Chlorella vulgaris 87/1 are described. Different proteases can be used for production of hydrolysates from ethanol extracted algae. The influence of reaction parameters on hydrolysis of extracted biomass with pancreatin was considered, and the composition of hydrolysates (Cv-PH) was investigated in relation to the starting materials. Significant changes in the degree of hydrolysis were observed only during the first 2h and it remained constant throughout the process. An enzyme-substrate ratio of 30-45 units/g algae, an algae concentration of 10-15% and pH values of 7.5-8.0 could be recommended. Differences in the chromatographic patterns of Cv-PH and a hot-extract from Chlorella biomass were observed. Adequate amounts of essential amino acids (44.7%) in relation to the reference pattern of FAO for human nutrition were found, except for sulfur amino acids. Cv-PH could be considered as a potential ingredient in the food industry. 相似文献
13.
Generation of transgenic plants of a potential oilseed crop Camelina sativa by Agrobacterium-mediated transformation 总被引:2,自引:0,他引:2
Camelina sativa is an alternative oilseed crop that can be used as a potential low-cost biofuel crop or a source of health promoting omega-3
fatty acids. Currently, the fatty acid composition of camelina does not uniquely fit any particular uses, thus limit its commercial
value and large-scale production. In order to improve oil quality and other agronomic characters, we have developed an efficient
and simple in planta method to generate transgenic camelina plants. The method included Agrobacterium-mediated inoculation of plants at early flowering stage along with a vacuum infiltration procedure. We used a fluorescent
protein (DsRed) as a visual selection marker, which allowed us to conveniently screen mature transgenic seeds from a large
number of untransformed seeds. Using this method, over 1% of transgenic seeds can be obtained. Genetic analysis revealed that
most of transgenic plants contain a single copy of transgene. In addition, we also demonstrated that transgenic camelina seeds
produced novel hydroxy fatty acids by transforming a castor fatty acid hydroxylase. In conclusion, our results provide a rapid
means to genetically improve agronomic characters of camelina, including fatty acid profiles of its seed oils. Camelina may
serve as a potential industrial crop to produce novel biotechnology products. 相似文献
14.
In vitro rearing of Eucelatoria bryani Sabrosky (Diptera: Tachinidae) was made more efficient and economical. Absorbent cotton, used as a support to replace more expensive agar in an artificial medium, produced yields of adults equal to those reared on the agar-based medium. The weights of pupae from the cotton-supported medium were about 16% lighter than were the weights of pupae from the agar-based medium. Evaluation of diet volumes (100, 200 and 250 l) for individually reared flies revealed that highest adult yields (46.3%) were obtained when 200 l per maggot of agar-based diet were used in each well of microtiter plates; this is equivalent to 2,315 adults per liter of diet. The tachinids were small and the sizes were equal to those obtained when 10–15 maggots parasitize a single host. Costs could not be reduced by deleting free amino acids from the medium fed to older maggots because free amino acids are essential dietary ingredients for third instars of E. bryani. 相似文献
15.
为探讨米老排(Mytilaria laosensis)叶片的潜在利用价值和开发前景,对其叶片的营养成分进行了测定.结果表明,9 a生植株的幼嫩叶片中粗蛋白、粗脂肪和水分含量显著低于成熟叶片;2 a生和10 a生米老排叶片的膳食纤维含量均超过50%,总糖含量为15.04%~16.25%;幼树叶片的维生素C含量[1651m... 相似文献
16.
Graham Noctor Gaëlle Bergot Caroline Mauve Dorothée Thominet Caroline Lelarge-Trouverie Jean-Louis Prioul 《Metabolomics : Official journal of the Metabolomic Society》2007,3(2):161-174
Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) has become a promising technique for simultaneous
and rapid analysis of small metabolites in complex mixtures. The aim of this work was to establish the quantitative nature
of the information generated by amino acid analysis of crude leaf extracts using GC-TOF-MS. Dried aliquots of methanol/water
extracts of Arabidopsis leaves were analysed in parallel by GC-TOF-MS following trimethylsilylation or high performance liquid chromatography and
fluorescence detection of o-phthaldialdehyde derivatives (OPA-HPLC). Twenty amino acids could be routinely detected in leaf extracts by both methods.
Because of instability of some trimethylsilylated derivatives, all GC-TOF-MS analyses were performed within a window of 2 h
30 min following derivatization. Repeatability studies showed that relative standard deviations for multiple injections of
a single extract were below 20% for both techniques, though significantly smaller for OPA-HPLC. Similar between-extract variability
and condition-independent biological variation were detected by OPA-HPLC and GC-TOF-MS, and both techniques detected similar
environmentally induced changes in four major amino acids. Recovery of standard compounds through the extraction procedure
was between 80% and 120% for OPA-HPLC but more variable when analysed by GC-TOF-MS. When quantified on the basis of tissue
fresh weight according to response factors of mixed standards, the two techniques gave consistent values for a number of amino
acids but divergent values for others. Taken together, the results suggest GC-TOF-MS analysis of Arabidopsis leaves with the present protocol can be used for absolute quantification of 4–7 amino acids, accurate relative quantification
of 8–11 amino acids, and more limited quantification for five compounds of this class. 相似文献
17.
Summary Environmental and management factors can influence the protein concentration of forages, significantly altering specific amino acid content. Drought, high rates of fertilizer N and the presence of a fungal endophyte have been associated with significant alterations in plant N metabolites and animal performance problems on tall fescue. A controlled environment study was conducted to examine the influence of N fertilization (10 and 100 gN/g) and water regime (low and adequate soil water availability) upon the distribution and concentration of amino acids in endophyte infected tall fescue (Festuca arundinacea, Schreb.) herbage. Tall fescue tissue was collected from three replicates of each treatment, quick frozen in liquid N and lyophilized. Two insoluble (RI, structural residue; RII, membrane residue) and two soluble (SI, soluble protein; SII, low molecular weight N compounds) fractions were collected. Amino acid analyses of acid hydrolysates of fractions showed that application of 100 N significantly increased the concentration (per unit dry weight) of all amino acids in the entire plant, with an average increase of about 55%. Application of 110 N increased the concentrations of most amino acids in fractions RI, RII, and SI, but only aspartate-asparagine, glutamate-glutamine, alanine, threonine, serine, valine and proline in fraction SII. Fraction RI contained about 65% of total amino acids under 10 N and 55% under 110 N even though N level did not alter dry matter distribution among fractions. While the amount of dry matter was least in SI, amino acids in the fraction ranged from 8% (leucine, 10 N) to 20% (lysine, 110 N) of the total amount of specific amino acids recovered. Significant increases in proline, glutamate, aspartate, serine, valine, threonine, alanine and phenylalanine concentration occurred under low soil-water availability compared with adequate water conditions. Basic amino acids including histidine, arginine and lysine increased with increased N and with water stress at each N level. Application of N increased amounts, and water stress influenced distribution of amino acids among the fractions of tall fescue herhage. Nitrogenous components, such as non-protein amino acids which could influence plant nutritive quality, were increased in fraction SII by increased N and water stress. 相似文献
18.
Salicylic acid was used as a probe for .OH formed during reperfusion of the ischemic myocardium. .OH adds to the phenolic ring of salicylate to yield dihydroxybenzoic acid species. The two principal dihydroxybenzoic acids formed are the 2,3- and 2,5-derivatives and can be isolated and quantitated using HPLC combined with electrochemical detection. In these experiments, dihydroxybenzoic acids were detectable in the f molar range. Rat hearts were perfused in the Langendorff mode with Krebs-Henseleit buffer containing 100 microM salicylate. Following 20 min of global ischemia a 173% increase in tissue content of 2,5-dihydroxybenzoic acid was detected after 2.5 min of reperfusion. The duration of ischemia did not significantly affect tissue content of 2,5-dihydroxybenzoic acid peaked at 250 to 300% of control within 2.5 min of reperfusion. The inclusion of 100 microM salicylate in the perfusion buffer had no effect on myocardial function during the duration of the experiments. The results indicate that salicylate can be used as a very sensitive probe for .OH in the isolated ischemic heart. 相似文献
19.
A novel cryptic plasmid, pMP1, from an environmental Vibrio vulnificus MP-4 isolated from Mai Po Nature Reserve in Hong Kong, has been characterized. The 7.6-kb plasmid had guanine–cytosine content
of 40.03% and encoded four open reading frames (ORFs) with >100 amino acids. The predicted protein of ORF1 contained 478 amino
acids showing 29% identity and 50% similarity over 309 amino acids to the integrase of Vibrio cholerae phage VP2. ORF2 encoded a putative protein of 596 amino acids, which were 23% identity and 42% similarity over 455 amino
acids to the tail tape measure protein TP901 of Chromohalobacter salexigens phage. ORF3 and ORF4 encoded putative proteins of 103 and 287 amino acids, respectively, but showed no homologies to any
known proteins. Further experiments indicated that a 3.2-kb fragment from EcoRI digestion could self-replicate. Analysis indicated that a sequence upstream of ORF4 had the features characteristic of
theta-type replicons: AT-rich region, six potential direct repeats (iterons) spaced approximately two DNA helical turn apart
(about 23 bp), two copies of 9 bp dnaA boxes, three Dam methylation sites, and five inverted repeats. Complementation experiments confirmed that the protein encoded
by ORF4 was required for plasmid replication. We propose that ORF4 encode a new type of Rep protein and pMP1 is a new type
of theta plasmid. 相似文献
20.
Ernest R. M. Kay 《Biotechnic & histochemistry》1953,28(1):41-44
A staining mixture consisting of 0.57% methyl green and 0.1 1 % pyronin B (calculated from the actual dye content) dis- solved in glycerol, 20 ml.; 2% aqueous phenol, 100 ml.; and 95% ethanol, 25 ml., was found to be optimum for differentiating cell components containing desoxypentose and pentose nucleic acids. The stain can be used for either fresh suspensions or unfixed dried smears of tissue homogenates. Nuclei are stained bright blue, and nucleoli and cytoplasmic particles, bright pink. 相似文献