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Nitric oxide (NO) is a potent regulator in the cardiovascular system; it is generated by the nitric oxide synthase (NOS) family of proteins. NO produced in endothelial cells plays a crucial role in vascular functions. The aim of this study was to clarify the effect of diabetes on aortic NO synthesis in a model of genetic hypertension and determine whether captopril modulates this effect. Diabetes was induced in ten weeks old spontaneously hypertensive rats (SHR) by streptozotocin injection. The rats were allocated into 3 groups: control group 1, non-diabetic SHR; group 2, diabetic SHR; group 3, diabetic SHR group receiving captopril at 80 mg/kg in drinking water for 4 weeks. Mean blood pressure (MBP) was measured once a week by tail-cuff method. Aortic NO metabolities (nitrite/nitrate) and endothelial NOS (NOS-3) were assayed by Griess reaction and by immunoblotting and immunohistochemistry, respectively. There was a significant decrease in nitrite/nitrate (NOx) in aortas of diabetic SHR compared with controls. The decrease of aortic NOx in diabetic SHR was accompanied by a decrease in NOS-3 expression. Captopril treatment reduced MBP without affecting either NOx level or NOS-3 expression in aortas of diabetic SHR. We conclude that STZ-induced diabetes decreased NO in aortas of SHR that may reflect endothelial cell dysfunction; captopril administration decreased MBP without affecting NO level in aortas of diabetic SHR which suggest that the blood pressure-lowering effects of captopril were independent of NO. 相似文献
3.
Lopatina T. V. Medvedeva N. I. Baikova I. P. Iskhakov A. S. Kazakova O. B. 《Russian Journal of Bioorganic Chemistry》2019,45(4):292-301
Russian Journal of Bioorganic Chemistry - A five-stage synthesis of azepanobetulin from betulin with a total yield of 47% has been carried out. The acylation of azepanobetulin with anhydrides or... 相似文献
4.
Cloning and sequencing of inulinase and β-fructofuranosidase genes of a deep-sea Microbulbifer species and properties of recombinant enzymes 总被引:1,自引:0,他引:1
Kobayashi T Uchimura K Deguchi S Horikoshi K 《Applied and environmental microbiology》2012,78(7):2493-2495
An inulinase-producing Microbulbifer sp. strain, JAM-3301, was isolated from a deep-sea sediment. An inulin operon that contained three open reading frames was cloned and sequenced. Two of the three genes were expressed. One product was an endo-inulinase, and the other was a β-fructofuranosidase. Both enzymes worked together to effectively degrade inulin. 相似文献
5.
Studart-Guimarães C Gibon Y Frankel N Wood CC Zanor MI Fernie AR Carrari F 《Plant molecular biology》2005,59(5):781-791
Despite the central importance of the TCA cycle in plant metabolism not all of the genes encoding its constituent enzymes
have been functionally identified. In yeast, the heterodimeric protein succinyl CoA ligase is encoded for by two single-copy
genes. Here we report the isolation of two tomato cDNAs coding for α- and one coding for the β-subunit of succinyl CoA ligase.
These three cDNAs were used to complement the respective Saccharomyces cerevisiae mutants deficient in the α- and β-subunit, demonstrating that they encode functionally active polypeptides. The genes encoding
for the subunits were expressed in all tissues, but most strongly in floral and leaf tissues, with equivalent expression of
the two α-subunit genes being expressed to equivalent levels in all tissues. In all instances GFP fusion expression studies
confirmed an expected mitochondrial location of the proteins encoded. Following the development of a novel assay to measure
succinyl CoA ligase activity, in the direction of succinate formation, the evaluation of the maximal catalytic activities
of the enzyme in a range of tissues revealed that these paralleled those of mRNA levels. We also utilized this assay to perform
a preliminary characterisation of the regulatory properties of the enzyme suggesting allosteric control of this enzyme which
may regulate flux through the TCA cycle in a manner consistent with its position therein. 相似文献
6.
David J. Anderson Robert J. Reischer Arlen J. Taylor William J. Wechter 《Nucleosides, nucleotides & nucleic acids》2013,32(5):499-512
Abstract The synthesis of oligonucleotides of 2'deoxyuridine containing both the natural D-2'deoxyribose and the unnatural L-2'deoxyribose is described. Units up to the 18-mer have been made via a modified triester procedure and characterized by HPLC. 相似文献
7.
Rate of utilization of glucose and `compartmentation'' of α-oxoglutarate and glutamate in rat brain 总被引:3,自引:3,他引:0
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M. K. Gaitonde 《The Biochemical journal》1965,95(3):803-810
1. The rate of incorporation of 14C into pyruvate, α-oxoglutarate, lactate and glucose of rat tissues was measured after the subcutaneous injection of uniformly labelled glucose. 2. In rat brain the specific radioactivities of lactate and glucose were similar to that of alanine. In liver the specific radioactivity of glucose was considerably higher than that of lactate or alanine. 3. The specific radioactivities of α-oxo acids of rat brain were lower than those of corresponding amino acids, alanine and glutamate. These findings have been explained in relation to metabolic compartments in vivo. 4. The approximate estimated rate of glucose utilization in rat brain in vivo is 0·96μmole/g. of brain/min. 相似文献
8.
In summer-autumn of 2003–2004, the ichthyoplankton of the Sea of Okhotsk comprised 35 species. In this period the most widely distributed and numerous were larvae of the lord Hemilepidotus gilberti, the Pacific stout sand lance Ammodytes hexapterus, and the Sakhalin dab Limanda sakhalinensis. The maximum catches of fish larvae were attributed to coastal waters off eastern Sakhalin and to the shelf of the northern part of the Sea of Okhotsk. In November of 2003, the ichthyoplankton of the Sea of Japan was represented by fish larvae belonging mainly to the boreal ichthyocomplex. The catches consisted predominantly of larvae of the arabesque greenling Pleurogrammus azonus, the ronquil Bathymaster derjugini, and the rockfish Sebastes owstoni. Fish larvae and fry in the northwestern part of the Sea of Japan were caught principally within 43°–45° N and 137°–139° E above the depth 1500–2000 m. The food spectrum of fish larvae in the Sea of Okhotsk and the Sea of Japan comprised over 20 plankters of various size belonging to seven taxa. Irrespective of fish species, the food items common of all fish were copepods Pseudocalanus minutus and Oithona similis. The daily rations were calculated for mass species (Hemilepidotus gilberti, Ammodytes hexapterus, Hexagrammos stelleri, Pleurogrammus azonus, Bathymaster derjugini, and Sebastes owstoni). The larvae of all considered species in the Sea of Japan and in the Sea of Okhotsk fed predominantly in the light period of the day. 相似文献
9.
Several studies have shown that the physical state of the phospholipid membrane has an important role in protein-membrane interactions, involving both electrostatic and hydrophobic forces. We have investigated the influence of the interaction of the calcium-depleted, (apo)-conformation of bovine α-lactalbumin (BLA) on the integrity of anionic glycerophospholipid vesicles by leakage experiments using fluorescence spectroscopy. The stability of the membranes was also studied by measuring surface tension/molecular area relationships with phospholipid monolayers. We show that the degree of unsaturation of the acyl chains and the proportion of charged phospholipid species in the membranes made of neutral and acidic glycerophospholipids are determinants for the association of BLA with liposomes and for the impermeability of the bilayer. Particularly, tighter packing counteracted interaction with BLA, while unsaturation—leading to looser packing—promoted interaction and leakage of contents. Equimolar mixtures of neutral and acidic glycerophospholipids were more permeable upon protein binding than pure acidic lipids. The effect of lipid structure on BLA-membrane interaction and bilayer integrity may throw new light on the membrane disrupting mechanism of a conformer of human α-lactalbumin (HAMLET) that induces death of tumour cells but not of normal cells. 相似文献
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Low-frequency (0.5-2.5 Hz) and individually defined high-frequency (7-11 or 8-12 Hz; 11-15 or 14-18 Hz) oscillatory components of the electroencephalogram (EEG) burst activity derived from thiopental-induced burst-suppression patterns (BSP) were investigated in seven sedated patients (17-26 years old) with severe head injury. The predominant high-frequency burst oscillations (>7 Hz) were detected for each patient by means of time-variant amplitude spectrum analysis. Thereafter, the instantaneous envelope (IE) and the instantaneous frequency (IF) were computed for these low- and high-frequency bands to quantify amplitude-frequency dependencies (envelope-envelope, envelope-frequency, and frequency-frequency correlations). Time-variant phase-locking, phase synchronization, and quadratic phase couplings are associated with the observed amplitude-frequency characteristics. Additionally, these time-variant analyses were carried out for modeled burst patterns. Coupled Duffing oscillators were adapted to each EEG burst and by means of these models data-based burst simulations were generated. Results are: (1) strong envelope-envelope correlations (IE courses) can be demonstrated; (2) it can be shown that a rise of the IE is associated with an increase of the IF (only for the frequency bands 0.5-2.5 and 7-11 or 8-12 Hz); (3) the rise characteristics of all individually averaged envelope-frequency courses (IE-IF) are strongly correlated; (4) for the 7-11 or 8-12 Hz oscillation these associations are weaker and the variation between the time courses of the patients is higher; (5) for both frequency ranges a quantitative amplitude-frequency dependency can be shown because higher IE peak maxima are accompanied by stronger IF changes; (6) the time range of significant phase-locking within the 7-11 or 8-12 Hz frequency bands and of the strongest quadratic phase couplings (between 0.5-2.5 and 7-11 or 8-12 Hz) is between 0 and 1,000 ms; (7) all phase coupling characteristics of the modeled bursts accord well with the corresponding characteristics of the measured EEG burst data. All amplitude-frequency dependencies and phase locking/coupling properties described here are known from and can be discussed using coupled Duffing oscillators which are characterized by autoresonance properties. 相似文献
12.
A. Sharada Devi Tasneem Rehana A. S. Kolaskar M. W. Pandit 《Journal of biosciences》1989,14(2):133-142
Hydrophilicity index is used to locate antigenic determinants on two related groups of proteins-myoglobin and hemoglobin.
The data on 41 species (including 34 mammals) of myoglobin show that average hydrophilicity for the complete myoglobin molecules
as well as the average hydrophilicity for all hydrophilic regions put together seem to remain constant; the variation in the
size and location of the antigenic determinants in these species is very small indicating that the antigenic sites are not
shifted during evolution. In the case of both the proteins there is a good agreement between the antigenic sites picked up
by using hydrophilicity index and the experimentally determined antigenic sites. The data on 56 species of hemoglobin α-chains
and 44 species of hemoglobinβ-chains showed that although there are few sites on hemoglobin which have remained invariant during evolution, there is a
significant variation in other sites in terms of either a splitting of a site, or a drastic change in the hydrophilicity values
and/or a length of the site. Comparison of the hydrophilicity data on these two groups of proteins suggests that hemoglobins
which perform a variety of functions as compared to myoglobins are evolving faster than myoglobins supporting the contention
of earlier workers. 相似文献
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Birichevskaya LL Kvach SV Sivets GG Kalinichenko EN Zinchenko AI Mikhailopulo IA 《Biotechnology letters》2007,29(4):585-591
Enzymatic 5′-monophosphorylation and 5′-phosphatidylation of a number of β-l- and β-d-nucleosides was investigated. The first reaction, catalyzed by nucleoside phosphotransferase (NPT) from Erwinia herbicola, consisted of the transfer of the phosphate residue from p-nitrophenylphosphate (p-NPP) to the 5′-hydroxyl group of nucleoside; the second was the phospholipase d (PLD)-catalyzed transphosphatidylation of l-α-lecithin with a series of β-l- and β-d-nucleosides as the phosphatidyl acceptor resulted in the formation of the respective phospholipid-nucleoside conjugates.
Some β-l-nucleosides displayed similar or even higher substrate activity compared to the β-d-enantiomers. 相似文献
15.
The synthesis of the fully benzylated α- and β-d-glucopyranosyluronic esters of 1-benzyl N-benzyloxycarbonyl-l-aspartic and -glutamic acids and N-(tert-butoxycarbonyl)-l-phenylalanine, followed by hydrogenolysis, afforded the respective anomers of the 1-O-acyl-d-glucopyranuronic acids 2, 7, and 12. Esterification of both anomers of the N-acetylated derivatives of 2 and 7 by diazomethane was accompanied by glycosyl-bond cleavage, and, in the case of the α anomers, with concomitant 1→2 acyl migration to give, after O-acetylation, the 2-O-acyl O-acetyl methyl ester derivatives 5 and 10, respectively. Similarly, 12α yielded methyl 1,3,4-tri-O-acetyl-2-O-[N-(tert-butoxycarbonyl)-l-phenylalanyl]-d-glucopyranuronate and an analogue having a furanurono-6,3-lactone structure. Esterification of the C-5 carboxyl group, in 1-O-acyl-α-d-glucopyranuronic acids by methanol in the presence of the BF3?-MeOH reagent (1–1.5 equiv.) proceeded without acyl migration. By using this procedure, followed by acetylation, the N-acetylated derivative of 7α afforded methyl 2,3,4-tri-O-acetyl-1-O-(1-methyl N-acetyl-l-glutam-5-oyl)-α-d-glucopyranuronate, and 12α gave methyl 2,3,4-tri-O-acetyl-1-O-(N-acetyl-l-phenylalanyl)-α-d-glucopyranuronate; the formation of the latter involved cleavage of the tert-butoxycarbonyl group by BF3, followed by N-acetylation in the next step. 相似文献
16.
E. F. Annison R. E. Brown R. A. Leng D. B. Lindsay C. E. West 《The Biochemical journal》1967,104(1):135-147
1. Rates of entry and oxidation of a range of metabolites have been measured in tracheostomized sheep (diet, 800g. of lucerne chaff and 100g. of maize/day) by combining isotope-dilution techniques with the continuous measurement of total respiratory gas exchange, and 14CO2 production during the intravenous or intraruminal infusion of 14C-labelled substrates. 2. Mean entry rates in fed and starved (24hr.) sheep respectively, expressed as mg./min./kg. body wt.0·75, were: glucose, 5·0 (range 4·8–5·1, 2 observations) and 3·8 (3·2–4·2, 4); acetate, 10·8 (9·1–13·5, 4) and 5·8 (1); d(−)-β-hydroxybutyrate, 1·4 (1) and 1·5 (0·8–2·4, 4); palmitate, oleate and stearate (starved sheep only) 1·0 (0·6–1·9, 7), 0·9 (0·2–1·6, 10) and 0·9 (0·5–1·1, 11) respectively. 3. Production rates of propionate and butyrate in continuously feeding sheep were 6·4 (4·7–8·3, 4) and 4·3 (3·4–6·1, 4) mg./min./kg.0·75 respectively, and in starved (24hr.) sheep were 2·5 (2·2–2·9, 2) and 1·0 (0·8–1·2, 2) mg./min./kg.0·75 respectively. 4. Calculated terminal values for the specific radioactivity of respiratory 14CO2 during measurements of entry rates and production rates were used to calculate the contributions of individual substrates to overall oxidative metabolism. Mean values for fed and starved sheep respectively were: glucose, 9·1 (8·6–9·6, 2) and 11·2 (5·9–15·1, 4)%; acetate, 31·6 (26·8–38·1, 4) and 22·1 (1)%; d(−)-β-hydroxybutyrate, 10·4 (1) and 4·8 (1·9–7·7, 4)%; propionate, 23·0 (13·8–29·9, 4) and 7·1 (6·8–7·4, 2)%; butyrate, 16·5 (13·7–20·5, 4) and 5·3 (5·2–5·3, 2)%; palmitate, oleate and stearate (starved sheep only), 4·7 (2·0–7·7, 7), 4·0 (1·2–6·6, 10) and 4·4 (3·8–5·8, 9)% respectively. The sum of these values for individual substrates in fed and starved sheep, excluding that of β-hydroxybutyrate and after correction of the glucose value for the known interrelations of this substrate with propionate, accounted for 76% and 58% respectively of total production of carbon dioxide. 5. Calculations based on the proportion of substrate entry directly oxidized indicated that the substrates studied accounted for 63% (fed sheep) and 43% (starved sheep) of total energy expenditure measured by oxygen uptake. The contribution of β-hydroxybutyrate was excluded, and corrections were made for glucose–propionate interrelations, and for the different rates of oxidation of the methyl and carboxyl fragments of acetate. 6. The present results have been combined with those obtained earlier in this Laboratory to examine the relationships between rates of substrate entry and oxidation, and concentrations of substrate in blood. Rates of entry of acetate, glucose, d(−)-β-hydroxybutyrate, palmitate and oleate (but not stearate) were well correlated with concentration in blood, and substrate contribution to production of carbon dioxide showed a similar correlation to blood concentration, except with glucose. 7. It was concluded that the general technique is of potential value in providing valid quantitative parameters of animal metabolism. 相似文献
17.
Regulation of biosynthesis and intracellular localization of rice and tobacco homologues of nucleosome assembly protein 1 总被引:1,自引:0,他引:1
The nucleosome assembly protein 1 (NAP1) is considered to be a conserved histone chaperone, facilitating the assembly of nucleosomes in all eukaryotes. However, studies in yeast and animal cells also indicated that NAP1 proteins have diverse functions likely independent of nucleosome-assembly activity. Here, we describe the isolation and characterization of cDNAs encoding NAP1-like proteins from the monocotyledon rice ( Oryza sativa L.) and the dicotyledon tobacco ( Nicotiana tabacum L.). Northern-blot analysis demonstrated that the two rice NAP1-like genes are predominantly expressed in stem tissues such as root and shoot apical meristems as well as in young flowers. During the cell cycle, all four tobacco NAP1-like genes are highly expressed, with one of them showing a slightly increased expression at the G1/S transition. These results are consistent with a role for plant NAP1-like proteins in cell division. In vitro binding assays revealed that different NAP1-like proteins bind, with distinct relative binding strengths, to different classes of histone. Intracellular localization analyses showed that some NAP1-like proteins could be targeted into the nucleus whereas others are exclusively cytoplasm-localized. It is thus likely that different plant NAP1-like proteins have distinct functions in vivo. Plant NAP1-like proteins were observed to concentrate around the metaphase plate and in the phragmoplast, suggesting a role in mitotic events and cytokinesis. 相似文献
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The effects of carbohydrate supply and light on rhizosecretion during micropropagation of potato plantlets (Solanum tuberosum L., cv. ‘Iwa’) in liquid medium were investigated. Soluble protein content was higher in the spent medium for plantlets grown
under light conditions than in the dark. For those plantlets grown under light conditions and on different sugar-supplemented
media, they rhizosecreted the highest amount of soluble protein when grown in the presence of maltose, while they rhizosecreted
the lowest amount of soluble protein when grown on medium containing glucose. Moreover, plantlets grown under light and on
a medium containing sucrose were the most vigorous, and exhibited the highest levels of rhizosecreted acid phosphatase activity.
However, there was no direct relationship between plantlet growth and rhizosecretion. When plantlets were grown in the dark
and on medium containing maltose, a higher α-glucosidase activity was detected than those grown on medium containing sucrose.
These results suggested that rhizosecretion of certain proteins from plantlets grown in vitro might not require exposure to
light conditions. 相似文献
20.
The effects of surface and macromolecular interactions on the kinetics of inactivation of trypsin and α-chymotrypsin
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The autolysis of trypsin and α-chymotrypsin is accelerated in the presence of colloidal silica and glass surfaces. It is proposed that adsorption of the enzymes (favoured by electrostatic factors) results in a conformational change that renders the adsorbed enzyme more susceptible to proteolytic attack. Although the adsorbed enzymes are more susceptible to proteolysis, their activity towards low-molecular-weight substrates is not affected, indicating a relatively minor conformational change on adsorption. The rates of autolysis in solution (i.e. in `inert' vessels) are second-order for both trypsin and α -chymotrypsin, with rate constants of 13.0mol−1·dm3·s−1 for trypsin (in 50mm-NaCl at pH8.0 at 25°C) and 10.2mol−1·dm3·s−1 for α-chymotrypsin (in 0.1m-glycine at pH9.2 at 30°C). In glass vessels or in the presence of small areas of silica surface (as colloidal silica particles), the autolysis of both trypsin and α-chymotrypsin can show first-order kinetics. Under these conditions, saturation of the surface occurs and the fast surface proteolytic reaction controls the overall kinetic order. However, when greater areas of silica surface are present, saturation of the surface does not occur, and, since for a considerable portion of the adsorption isotherm the amount adsorbed is approximately proportional to the concentration in solution, second-order kinetics are again observed. A number of negatively charged macromolecules have been shown similarly to increase the rate of autolysis of trypsin: thus this effect, observed initially with glass and silica surfaces, is of more general occurrence when these enzymes adsorb on or interact with negatively charged surfaces and macromolecules. These observations explain the confusion in the literature with regard to the kinetics of autolysis of α-chymotrypsin, where first-order, second-order and intermediate kinetics have been reported. A further effect of glass surfaces and negatively charged macromolecules is to shift the pH–activity curve of trypsin to higher pH values, as a consequence of the effective decrease in pH in the `microenvironment' of the enzyme associated with the negatively charged surface or macromolecule. 相似文献