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1.
A study of the oxidation of butan-1-ol and propan-2-ol by nicotinamide-adenine dinucleotide catalysed by yeast alcohol dehydrogenase.
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1. The kinetics of oxidation of butan-1-ol and propan-2-ol by NAD+, catalysed by yeast alcohol dehydrogenase, were studied at 25 degrees C from pH 5.5 to 10, and at pH 7.05 from 14 degrees to 44 degrees C, 2. Under all conditions studied the results are consistent with a mechanism whereby some dissociation of coenzyme from the active enzyme-NAD+-alcohol ternary complexes occurs, and the mechanism is therefore not strictly compulsory order. 3. A primary 2H isotopic effect on the maximum rates of oxidation of [1-2H2]butan-1-ol and [2H7]propan-2-ol was found at 25 degrees C over the pH range 5.5-10. Further, in stopped-flow experiments at pH 7.05 and 25 degrees C, there was no transient formation of NADH in the oxidation of butan-1-ol and propan-2-ol. The principal rate-limiting step in the oxidation of dependence on pH of the maximum rates of oxidation of butan-1-ol and propan-2-ol is consisten with the possibility that histidine and cysteine residues may affect or control catalysis. 相似文献
2.
Phospholipase D stimulation is required for sphingosine-1-phosphate activation of actin stress fibre assembly in human airway epithelial cells. 总被引:2,自引:0,他引:2
In human airway epithelial cells, sphingosine-1-phosphate (SPP) and lysophosphatidic acid (LPA) stimulated the production of phosphatidic acid (PA), which was inhibited by the primary alcohol butan-1-ol, but not by the inactive butan-2-ol, clearly indicating phospholipase D (PLD) involvement. Both SPP and LPA stimulated actin stress fibre formation, which was also butan-2-ol-insensitive and inhibited by butan-1-ol. SPP-induced PLD activation and cytoskeletal remodelling were insensitive to brefeldin A and toxin B from Clostridium difficile, which conversely blocked the effect of LPA, suggesting that the monomeric GTPases ADP ribosylation factor (ARF) and Rho are involved in LPA, but not in SPP responses. Pertussis toxin inhibited SPP- but not LPA-induced effects. PLD activation and stress fibre formation by both lysolipids were abolished by the tyrosine kinase inhibitor genistein. Addition of PA to cells caused a massive stress fibre assembly. In conclusion, PLD is one of the signalling components linking SPP-receptor activation to assembly of actin stress fibres. 相似文献
3.
Addition of the animal ether phospholipid platelet-activating factor, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine, (PAF) stimulates medium acidification in cultured soybean (Glycine max L.) cells. The pH of the medium after 8–10 hours is on the average one pH unit lower than in controls. With fusicoccin an average pH difference of 1.7 units is reached. Phospholipids, glycerol, 1-oleyl-2-acetyl-sn-glycerol, 1-0-hexadecyl-sn-glycerol, and triolein at the same concentrations as PAF had no stimulatory effect on medium acidification. The detergents CHAPS and deoxycholate lead to alkalinization of the medium whereas lysophosphatidylcholine (LPC), a detergent with structural similarity to PAF, shows no effect.Abbreviations CHAPS
(3-((3-cholamylopropyl) dimethylamino)-1-propanesulfonate)
- DOC
deoxycholic acid
- FC
fusicoccin
- LPC
lysophosphatidylcholine
- OAG
1-oleyl-2-acetyl-sn-glycerol
- PAF
platelet-activating factor = 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine
- IAA
indole-3-acetic acid 相似文献
4.
B. Rao 《Prostaglandins & other lipid mediators》1979,18(1):93-100
In vitro synthesis of progesterone and estradiol-17β from endogenous precursors was studied in the placenta from women in early stage of gestation (< 7 weeks). Radioimmunoassay techniques were used to measure progesterone and estradiol-17β.It was shown that placental tissue from as early as six weeks of gestation can synthesize both progesterone and estradiol-17β in vitro. Prostaglandins F2α and E2 in concentration of 100 μg/ml of the incubation media did not have any significant effect on the in vitro synthesis of progesterone and estradiol-17β in the placental tissue.It seems unlikely that the abortifacient effect of natural prostaglandins PGE2 and PGF2α is due to their direct action on the synthesis of progesterone and estradiol-17β in the placenta. 相似文献
5.
Hilda M. Garcia Maria de los Angeles Martinez Roberto Vazquez Julio Delgado 《Biotechnology letters》1985,7(10):723-726
Summary A procedure for the transformation ofKluyveromyces lactis based on the Li salt method for introducing plasmid DNA into intact yeast cells is described. Contrary toSaccharomyces cerevisiae, lithium salts are dispensable for inducing competence inK. lactis. 2-Mercaptoethanol, a compound that stimulates transformation inS. cerevisiae, showed an opposite effect. inK. lactis. On the other hand, the presence of PEG 4000 and a heat shock were absolutely required to obtain high transformation efficiency. 相似文献
6.
Nelson Duran Jaime Rodriguez Andre Ferraz Victoriano Campos 《Biotechnology letters》1987,9(5):357-360
Summary
C. sitophila strain TFB-27441 showed 2–3 times higher lignolytic activity thanPhanerochaete chrysosporium (BKM-F-1767 strain). Lignin had a marked effect on the ligninase activity indicating that some induction or activation mechanism is involved in lignin degradation byC. sitophila. 相似文献
7.
Photosynthesis in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> Mutants with Reduced Chloroplast Number 总被引:7,自引:0,他引:7
We have used a class of Arabidopsis mutants altered in the accumulation and replication of chloroplasts (arc mutants) to investigate the effect of reduced chloroplast number on the photosynthetic competence of leaves. Each of the arc mutants examined (arc3, arc5, and arc6) accumulate only a few (2–15) large chloroplasts per mesophyll cell [K.A. Pyke and R.M. Leech (1992) Plant Physiology 99: 1005–1008]. The increased plastid size maintains a constant plastid to mesophyll cell volume, which has been suggested to compensate for the lower chloroplast number. In fact, we find that reduced chloroplast number has an effect on both the composition and structure of the photosynthetic apparatus, and that each arc mutant has an altered photosynthetic capacity, and we conclude that photosynthetic competence is dependent on proper chloroplast division and development. 相似文献
8.
Milvia Luisa Racchi 《Plant cell reports》1985,4(4):184-187
B and Pl are two genes involved in anthocyanin biosynthesis in maize (Zea mays) plant tissues. In this work the effect of B and Pl on pigment accumulation is analyzed in endosperm tissues, either cultured in vitro or scraped off from the seed. The results obtained indicate that the two genes play a different role in callus pigmentation: B exerts a qualitative change in pigment composition, while Pl controls the rate of pigment accumulation in the callus. Anthocyanin synthesis in all strains analyzed appears to be light independent. Two cases of instability in pigment production arisen in the endosperm cultures are described and discussed in relation to epigenetic variation in secondary metabolite content in plant tissue culture.Abbreviations BEAF
Benzene/ethyl acetate/formic acid (40:10:5)
- 2-4D
2,4-dichlorophenoxyacetic acid
- Wi
initial weight
- Wt
total weight 相似文献
9.
One evidence for a luteolytic role for prostaglandin F2α in the human is the increase in luteal PGF at times corresponding to luteolysis as reported earlier by us and other groups. There have been other contradictory reports on this point. In the present experiments we have measured the concentrations of PGE and PGF in 16 more human corpora lutea and have determined the capacity of those tissues to form PGE and PGF in vitro. PGF concentrations were highest in the mid luteal phase but were accompanied by high PGE concentrations. On the other hand, in the late luteal phase PGF concentrations, lower than in mid luteal but generally higher than in early luteal phase, were significantly higher than PGE concentrations. This pattern in PGE and PGF concentrations was also evident in the capacity of these tissues to form these compounds in vitro. In view of the known capacity of PGE2 to counteract the luteolytic effect of PGF2α, these variations in the relative concentrations of PGE and PGF during the luteal phase may be of significance in the process of luteolysis in the human. 相似文献
10.
11.
S. E. Petrović M. Škrinjar A. Bećarević I. F. Vujičić L. Banka 《Biotechnology letters》1990,12(4):299-304
Summary The aim of these investigations was to study the conditions for the production of extracellular lipases fromPenicillium
roqueforti S-86, which was isolated from a commercial sample of roqueforti chese type. As carbon sources there have been used the following compounds: 2% glucose, fructose and sucrosel 1% and 2% butterfat and 2% olive oil. Maximal amount of lipases was produced after six days of incubation grown in the medium with 2% of glucose, initial pH of medium 4.0 at 27°C. Cells ofPenicillium
roqueforti grown in the presence of bacto-peptone instead of (NH4)2SO4, as nitrogen source, synthesized maximum quantity of lipases after four days of incubation.The effect of temperature, pH, as well as mono, be and three valent cations: Na+, K+, Ca++, Mn++, Mg++ and Fe+++ on lipase activity was followed. 相似文献
12.
Mitochondrial morphology is regulated by conserved proteins involved in fusion and fission processes. The mammalian Optic atrophy 1 (OPA1) that functions in mitochondrial fusion is associated with Optic Atrophy and has been implicated in inner membrane cristae remodeling during cell death. Here, we show Drosophila Optic atrophy 1-like (Opa1-like) influences mitochondrial morphology through interaction with ‘mitochondria-shaping’ proteins like Mitochondrial assembly regulatory factor (Marf) and Drosophila Mitofilin (dMitofilin). To gain an insight into Opa1-like's network, we delineated bonafide interactors like dMitofilin, Marf, Serine protease High temperature requirement protein A2 (HTRA2), Rhomboid-7 (Rho-7) along with novel interactors such as Mortalin ortholog (Hsc70-5) from Drosophila mitochondrial extract. Interestingly, RNAi mediated down-regulation of hsc70-5 in Drosophila wing imaginal disc's peripodial cells resulted in fragmented mitochondria with reduced membrane potential leading to proteolysis of Opa1-like. Increased ecdysone activity induced dysfunctional fragmented mitochondria for clearance through lysosomes, an effect enhanced in hsc70-5 RNAi leading to increased cell death. Over-expression of Opa1-like rescues mitochondrial morphology and cell death in prepupal tissues expressing hsc70-5 RNAi. Taken together, we have identified a novel interaction between Hsc70-5/Mortalin and Opa1-like that influences cellular homeostasis through mitochondrial fusion. 相似文献
13.
Optimization and characterization of an extracellular polysaccharide produced byGlomerella
cingulata
Summary A new strain of the fungusGlomerella
cingulata has been isolated, which produces an extracellular highly viscous polysaccharide in a simple mineral medium. Optimum conditions for its production and properties are described. The polysaccharide produced was a glucan type. The viscosity remained stable during storage over a period of seven days. Large changes in temperature and pH have no effect on viscosity. 相似文献
14.
Miles J. Novy George Piasecki Benjamin T. Jackson 《Prostaglandins & other lipid mediators》1974,5(6):543-555
The hemodynamic effects of PGF2α, PGE2, and norepinephrine injected into the umbilical arterial circulation were compared in nine fetal lambs in utero. Umbilical blood flow was measured with radioactive microspheres and an electromagnetic flow transducer implanted on the distal aorta of the fetus after ligation of external iliac arteries and other accessible distal aortic branches.PGF2α and norepinephrine increased fetal arterial pressure and umbilical blood flow while umbilical vascular resistance increased slightly (PGF2α) or not at all (norepinephrine). PGE2 increased fetal arterial pressure, decreased umbilical blood flow, and exerted a profound active vasoconstrictor effect on the fetal placental bed. Our data taken together with the observations of others suggest that prostaglandins may play a role in the circulatory adaptations of the fetus at birth and that PGE2 in high concentrations is likely to have deleterious hemodynamic consequences in the fetus in utero. 相似文献
15.
The synthesis of PGC2 methyl ester is described. Comparison of the synthetic material with the methyl ester prepared from natural PGC2 showed the two to be identical, thus confirming the structure assignment. The physical and biological data of PGC2 methyl ester are presented.Horton and Jones have recently shown that PGA1 (Ic) and PGA2 (Ia) are deactivated on incubation with cats blood (1,2). Jones has proposed that this deactivation involves the enzymic conversion of PGA (I) to an 11,12-double bond isomer (PGC, II) which is subsequently isomerized by base to the inactive PGB (III) (3). Structure assignment of the PGC's in the earlier study were based on chromatographic mobilities and uv and mass spectrometric properties. We report here a total synthesis of PGC2 methyl ester (IIb). Comparison of the biological and physical properties of this material with those of diazomethane-esterified natural material confirms the earlier structure assignment for PGC2 (IIa). 相似文献
16.
Summary Some nutritional factors that affect lipase yields byRhizopus
delemar were studied. Dextrin proved to be the best carbon source when used at 1% level. Yeast extract was the best nitrogen source for lipase production. The presence of a lipidic source in the growth medium, at a level not higher than 2% resulted in higher enzyme production. Tween 80 exerted a positive effect on enzyme production, used in a range that goes from 0.02% to 2.00%. 相似文献
17.
We have analyzed the ability of single site insertion mutants of Rhizobium meliloti 1021 defective in various components of a high-affinity iron transport system to produce nodules, fix nitogen and promote plant growth. Our results indicate that a high-affinity iron transport system may significantly increase the ability of the differentiated form of the bacterium to fix nitrogen and induce an increase in plant growth.Abbreviations EDDA
ethylenediamine-N,N-bis(2-hydroxyphenylacetic acid)
- CAS
chrome azurol S 相似文献
18.
Dr. A. R. Reddy P. A. Peterson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1976,48(6):269-278
Summary Several stable germinal derivatives, with varied phenotypic expression have been recovered from testcrosses of four different a2 mutable alleles (a2m-7 8018, a2m-6 8144, a2m-6 8140, and a2m-1 1511) under the control of the En controlling-element system. These are colored, pale, and colorless aleurone types; the former two represent mutations of a2-mA2 type. The phenotypic variation among colored and pale derivatives has been confirmed by quantitative determination of anthocyanin content in the aleurone tissue of the kernels.The data suggest that significant variation exists between phenotypically similar colored derivatives arising from different mutable alleles as well as from the same source allele. Every tested colored derivative is significantly different from the pale, colorless, and colored control (W22 color converted line). Genetic analysis of these colored derivatives suggests that all of them contain one or more En and, hence, they are characterized as permanent changes of a nonresponsive (nr) type. Their frequencies are variable among the testcrosses.Similarly, the pale derivatives, which are clearly different from colored and colorless, also show significant differences in terms of anthocyanin content. Significant differences exist between pales arising from the same allele as well as between pales arising from different alleles. All the tested pales are significantly different from colorless and colored derivatives. Thus, the pales, as well as colored derivatives, represent a differential impairment of anthocyanin synthesis in the aleurone tissue. The genetic analysis confirmed that all the pales, except the pales of a2m-1 1511, lack the capacity to respond to En. These pale derivatives can be with or without En.Qualitative differences among the colored, pale, and colorless types have been investigated by thin-layer chromatographic and spectroscopic techniques. The results suggest that there are no qualitative differences, in terms of anthocyanin pigments, between colored, pale, and colored control. All accumulate the same anthocyanins (namely, cyanidin-3-glucoside and pelargonidin-3-glucoside in appropriate proportions depending upon the Pr and pr constitution).Journal Paper No. J-8431 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011. Project No. 1884: Support from NSF GB38328. 相似文献
19.
We have demonstrated the capacity of isolated follicles from estrous rabbits to synthesize prostaglandins in vitro and to respond to gonadotropins added to the incubation medium with an increased accumulation of these lipids. The increase in both prostaglandins became apparent only after 5 hours of incubation. The effect was specific for hormones with LH activity and the threshold dose of LH appeared to be 0.005 μg/ml. In addition, we have shown that cyclic AMP (0.02 M) added to the incubation medium also increased prostaglandin in this in vitro system and appears to be a likely mediator of this action of LH. 相似文献
20.
《Cellular signalling》2014,26(9):1928-1934
The proteins Bax and Bak are central in the execution phase of apoptosis; however, little is known about the partners involved in the control of this complex process. Here, we show that mitochondrial Bak is incorporated into a VDAC2/Mtx1/Mtx2 multi-protein complex in both resting and dying cells. VDAC2 is a porin that has previously been described as a partner of Bak while Mtx1 and Mtx2 are two proteins of the mitochondrial sorting and assembly machinery (SAM) that have been implicated in TNF-induced apoptosis. We show that, after the induction of apoptosis, Bak switches from its association with Mtx2 and VDAC2 to interact with Mtx1. 相似文献