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1.
Bioluminescence rises very rapidly in the later stages of growth of Beneckea harveyi due to the induction of luciferase activity. This enzyme catalyzes the in vitro oxidation of FMNH2 and a long chain aliphatic aldehyde resulting in the emission of light. The present experiments report the discovery of an aldehyde dehydrogenase in Beneckea harveyi which is remarkably similar to luciferase in its specificity for long chain aliphatic aldehydes. Furthermore, the activity of this enzyme is shown to be induced at the same time as luciferase thus providing strong evidence for a functional implication of aldehyde dehydrogenase in the bioluminescent system of Beneckea harveyi.  相似文献   

2.
Phosphorylation of the 18,500 dalton light chain of myosin and conversion of phosphorylase b to a were examined in relation to isometric tension development. Following a l sec tetanic contraction, light chain phosphate content increased from a pre-tetanic value of 0.10 to 0.75 mol phosphate/mol at 7 sec; phosphorylase a activity (ratio of activity ?5′AMP+5′AMP) increased from 0.03 to 0.42 at 4 sec and decreased to control values within 20 sec. Light chain phosphate content, however, declined much more slowly and correlated to post-tetanic potentiation of peak twitch tension. Our results suggest light chain phosphorylation is not obligatory for contraction but may play a role in post-tetanic potentiation.  相似文献   

3.
With ethanol as substrate, N-n-alkylformamides and mono-n-alkylureas, like fatty acid amides, inhibited horse liver alcohol dehydrogenase uncompetitively, presumably by forming ternary complexes with the enzyme - reduced nicotinamide adeninedinucleotide binary complex. Compounds with 11- or 12-atom chains were better inhibitors than longer or shorter chain compounds. In vivo (mice), the urea derivatives were ineffective, as were the amides, with the exception of butanamide; the latter compound was less active than iso-butanamide. Formamides with 4- to 12-atom chains were active in vivo but, unlike in vitro, the shorter chain compounds were the most potent. A variety of branched-chain alkyl-, cyclic alkyl- and arylalkylamides and N-substituted formamides also inhibited alcohol dehyrogenase in vitro.  相似文献   

4.
The light chain type, immunoglobulin class and when possible, heavy chain subclass of eleven monoclonal human cryoglobulins were correlated with the variable region subgroup of their light chains. The variable region subgroups were assigned by determining the primary amino acid sequence for the first 15 amino-terminal residues of these light chains. 55 IgM cryoglobulins which react with human IgG had light chains of the variable region-III kappa chain subgroup (vK-III). 44 IgG and 22 IgM cryoglobulins with undefined antibody specificity had both lambda and kappa light chains none of which were vK-III. The data support the concept that there is marked restriction of the IgM anti-IgG antibody response to the IgG auto-antigen.  相似文献   

5.
The antiinflammatory activity of a homologous series of α-alkyl substituted [4-(1-oxo-2-iso-indolinyl)-phenyl]-acetic acid has been assayed by some invitro and invivo tests.These compounds were shown to be particularly active in inhibiting prostaglandin biosynthesis from bovine seminal vesicles, and their potency was seen to increase as the size of the substituents in the side chain increased.The antiinflammatory activity invivo is not correlated with invitro inhibition of PG-synthetase. Discussion of the data takes into account the plasma protein binding and pharmacokinetics of these compounds.  相似文献   

6.
We have studied the synthesis of poly(ADP-ribose) by nuclei isolated from Xenopuslaevis embryos at different stages of development. Determination of the total chain length of poly(ADP-ribose) molecules by hydroxylapatite column chromatography generally gave higher values than when the radioactive portions of these molecules, synthesized invitro, were measured by poly(ethyleneimine)-cellulose thin layer chromatography, after snake venom phosphodiesterase digestion. The results show that most of the poly(ADP-ribose) synthesized invitro is a covalent elongation of molecules previously initiated invivo.  相似文献   

7.
Both invitro and invivo, increased exposure to visible light decreases the regenerability of the visual pigment. Isolated opsin irradiated with increasing periods of white light decreased in pigment formation yields on combination with 9- or 11-cis retinal. The yield of regeneration of the visual pigment extracted from albino rats depended on the amount of light to which the animal had been exposed. Animals exposed to normal room light demonstrated lower regeneration yields than dark-reared animals, but these yields increased on dark adaption. Opsin from animals exposed to sunlamps did not regenerate any pigment. On dark adaption, the pigment yields increased but the opsin level remained below that for the control group.  相似文献   

8.
Triplet states in photosynthesis   总被引:5,自引:0,他引:5  
A comparison of zero field splitting (ZFS) and spin polarization of triplet spectra of bacteriochlorophyll a in vitro and in vivo provides support for the special pair model of photoreactive chlorophyll in photosynthetic bacteria. Spin polarization of the triplet spectra is a new and unique probe of primary events in the light conversion act in photosynthesis.  相似文献   

9.
Hydrogenase activity in the thermophilic cyanobacterium, Mastigocladuslaminosus was studied both in vivo and in vivo hydrogen consumption required oxygen but not light, was about ten-fold higher than in mesophilic cyanobacteria, and was relatively insensitive to carbon monoxide. H2-supported acetylene reduction in reductant-limited cultures was a light-dependent, but O2-independent reaction. In vitro hydrogen evolution was unaffected by carbon monoxide, and this activity could be partially purified using a procedure developed for Anabaena cylindrica.  相似文献   

10.
Taurine is believed to be a modulator of membrane excitability in muscle and a neuroinhibitory transmitter in the central nervous system. The retina and pineal contain relatively large quantities of taurine. Taurine levels in the retina are reported to be responsive to variations in lighting conditions. We report here a carcadian rhythm for taurine in the mature male rat pineal gland. The maximum taurine concentration occurs at the midpoint of the light period, 24 ± 1.9 nmoles/gland, and the minimum at the beginning of the dark period, 13.9 ± 1.6 nmoles/gland. Sympathectomy by bilateral superior cervical ganglionectomy lowered pineal taurine levels. Constant light and blinding had no effect. Taurine was demonstrated to be taken up by the pineal gland invitro in organ culture. The uptake was saturable, Km = 2.0 mM, and sodium dependent. The close structural analogs hypotaurine and β-alanine inhibited taurine uptake but α-alanine did not. We have demonstrated a circadian rhythm for taurine content in the rat pineal gland and the presence of a sodium-dependent transport system for taurine in the pineal invitro in organ culture.  相似文献   

11.
The adenine nucleotide translocase, the transport protein for ADP and ATP, located in the inner mitochondrial membrane is an important site for the regulation of cell metabolism. Inhibition of the adenine nucleotide translocase by long chain fatty acyl CoA esters demonstrated invitro may also occur invivo when the complete oxidation of fatty acids by the myocardium has been compromised during ischemia. Reversal of this biochemical lesion may be of benefit in the preservation of the ischemic myocardium.  相似文献   

12.
Lactate dehydrogenase-C (LDH-C) mRNA was purified from DBA2 mouse testes and translated invitro. First, the LDH-C synthesizing polysomes were isolated by double immunoprecipitation using specific anti-LDH-C and anti-horse immunoglobulin antibodies. Extraction of mRNA was made from the isolated polysomes using hot sodium dodecyl sulfate-phenol method at alkaline pH. In a wheat germ cell-free translation system, the mRNA coded for a polypeptide chain that could be immunoprecipitated with specific anti LDH-C antibody and comigrated with authentic LDH-C in sodium dodecyl sulfate-polyacrylamide gel electrophoresis.  相似文献   

13.
Synthesis and biological activity of 2′-acetyltaxol and 7-acetyltaxol are reported. Activity is measured invivo by cytotoxicity toward the macrophage-like cell line J774.2, and invitro by promotion of microtubule assembly in the absence of exogenous GTP. Addition of an acetyl moiety at C-2′ results in loss of invitro activity but not cytotoxicity. The properties of 7-acetyltaxol are similar to those of taxol in its effects on cell replication and on invitro microtubule polymerization. Therefore a free hydroxyl group at C-7 is not required for invitro activity and this position is available for structural modifications.  相似文献   

14.
Gaps in daughter-strand deoxyribonucleic acid (DNA) synthesized after exposure of wild-type Escherichiacoli to ultraviolet light are filled during reincubation. In this study the dnaG, dnaC, and dnaA gene products have been examined for their role in postreplication repair. These gene products are unique in their specific control of certain types of DNA synthesis: initiation of rounds of replication and chain propagation. Initiation of rounds of replication is not essential to gap filling; however, chain propagation by short DNA piece initiation appears to be essential for gap filling.  相似文献   

15.
G J Smith  P H Pearce  I T Oliver 《Life sciences》1976,19(11):1763-1775
A particulate factor of rat liver is described which interconverts three forms of rat liver cytosolic tyrosine aminotransferase invitro with no alteration of enzyme activity. The factor appears to be a heat- and pH-sensitive lysosomal protein. The interconversion process is stimulated invitro by 2.5 mM MgCl2 and 2.5 mM ATP. Asparate aminotransferase multiple forms are also susceptible to invitro interconversion by the lysosomal factor. The properties of the factor explain several anomalous effects of invitro manipulation on the tyrosine aminotransferase forms which have been reported in the literature and implicate the form interconversion in the degradation of tyrosine aminotransferase.  相似文献   

16.
α-Glucosidase was membrane bound during exponential growth of Bacilluslicheniformis but was released into the medium during stationary phase. It could be partially removed from exponential phase cells by washing with NaCl (0.5 M). α-Amylase was exclusively extracellular and could not be detected in cells. Polysomes were prepared from exponential phase cells and separated into membrane bound and soluble fractions. Invitro chain completion and immunoprecipitation showed that α-glucosidase and α-amylase were synthesized by membrane bound and not by soluble ribosomes.  相似文献   

17.
The pesticide o,p'-DDT stimulates the production of a specific uterine protein, the so-called induced protein or IP, normally associated with an estrogenic response of the uterus. Invivo stimulation of IP production is observed 1 hour after the administration of 250 mg/kg of o,p'-DDT to immature rats. Invitro stimulation of IP production is observed after a 1 hour incubation of uteri with 100 μM o,p'-DDT. This invitro response is blocked by Actinomycin D. In contrast to o,p'-DDT, which binds to the cytoplasmic estrogen receptor and stimulates IP production, p,p'-DDT which does not bind well to the estrogen receptor does not stimulate IP production invitro. These findings represent the first report of an estrogenic effect of o,p'-DDT in a completely invitro system.  相似文献   

18.
19.
N-Terminal amino acid analysis of the intracellular form of tetanus toxin revealed proline as the single terminal residue present in significant quantities. In agreement with new concepts on the structure of tetanus toxin, a second N-terminal amino acid (leucine) was exposed upon conversion to the extracellular form of the toxin molecule. These results were corroborated by analysis of the separate polypeptide chains of the extracellular toxin, and it is concluded that the light chain polypeptide constitutes the N-terminal region of the single chain toxin molecule originally synthesized by the bacterial cell. Treatment of the intracellular tetanus toxin with trypsin in vitro resulted in the exposure of amino acids in addition to those found after conversion to the extracellular form effected by the bacterial protease during fermentation.  相似文献   

20.
Fatty acid hydroperoxide lyase (HPO lyase) was found in green and non-green tobacco cells cultured in vitro. The HPO lyase activity in non-green cells was 13-12 of that in green cells. When the cells were transferred from the light to dark conditions or vice versa, cells turned non-green or green according to the light conditions. The HPO lyase activity also changed according to the light conditions, but the changes in HPO lyase activities were not proportional to the changes in chlorophyll contents. These results suggest that at least two types of HPO lyases are present in the green cells. One type of HPO lyase is perhaps common both to the green and non-green cells; another one is chloroplastic. The fatty acid compositions of cells and substrate specificities of HPO lyase differed between green and non-green cells.  相似文献   

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