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1.
Characterization and sequence determination of six aprotinin homologues from bovine lungs 总被引:2,自引:0,他引:2
Six Kunitz inhibitors, which are dissimilar to aprotinin, can be isolated from bovine lungs. These homologues cannot be distinguished from aprotinin, in respect to their inhibitory specificity. They have, however, different amino-acid compositions and a different degree of basicity. The entire primary structures of these inhibitors were elucidated by automated Edman sequencing. Besides the known Glp-1-aprotinin another aprotinin homologue (des-Ala58-aprotinin) was isolated, which could result from a different proteolytic processing of the bovine aprotinin precursor. The other homologues can be denoted as aprotinin isoinhibitors, showing several amino-acid replacements compared to aprotinin and which also appear in the area of the contact region. 相似文献
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Beta-endorphin secretion by human peripheral blood mononuclear cells: regulation by glucocorticoids 总被引:3,自引:0,他引:3
Corticotropin-releasing factor (CRF), a 41-aminoacid neuropeptide, can induce lymphocytes to production of beta-endorphin (beta E). Furthermore, the neuropeptide Arginine-Vasopressin (AVP) can enhance CRF-induced production of beta E. We have demonstrated that CRF acts by stimulating monocytes to production of the cytokine interleukin-1 (IL-1). IL-1 can in its turn activate the lymphocytes to secretion of beta E. Here we demonstrate that the glucocorticoid analogue dexamethasone is capable of modulating CRF-induced beta E secretion by lymphocytes. It appeared that dexamethasone can inhibit secretion of lymphocyte-derived beta E. The mechanism by which dexamethasone exerts its inhibitory activity is by blocking CRF-induced production of IL-1, thereby preventing induction of beta E secretion by B cells. These results support the concept that peptide hormones and glucocorticoids are mediating a reciprocal modulation of neuroendocrine and immunological activities. 相似文献
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《Comparative biochemistry and physiology. B, Comparative biochemistry》1981,68(3):615-617
- 1.1. Lysozyme activity was detected for the first time in populations of Acarus siro L., Glycyphagus destructor (Schrank), G. domesticus (De Geer), Rhizoglyphus callae Oudemans, R. robini Claparede and Tyrophagus longior (Gervais) (Arthropoda: Acari).
- 2.2. No significant differences between the activity in different populations was observed.
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The effect of opioid peptides on the production of reactive oxygen by neutrophils in a nonfractionated leukocyte suspension and in a purified fraction of peripheral blood neutrophils was studied. Selective ??- and ??-agonists of peptide origin were shown to stimulate the spontaneous and inhibit zymosan-induced (15 ??g/mL) LDCL (luminol-dependent chemiluminescence) reactions of neutrophils in leukocyte suspension. ??-Endorphin caused a weaker inhibitory effect on zymosan-induced (15 ??g/mL) LDCL, and the ??2-agonost deltorphin II stimulated zymosan-induced (15 ??g/mL) LDCL only for 25 min of the experiment. ??-Endorphin and selective ??- and ??-agonists did not affect spontaneous or inhibited zymosan-induced (15 and 150 ??g/mL) LDCL in a purified fraction of peripheral blood neutrophils. Therefore, opioid peptides play an essential role in direct and indirect regulation of the oxygen-dependent system of neutrophil granulocyte bactericidal activity. 相似文献
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广西兰科植物新记录 总被引:1,自引:0,他引:1
该文报道了广西兰科植物6个新记录物种,即日本对叶兰[Neottia japonica(Blume)Szlachetko]、吉氏羊耳蒜(Liparis tsii H.Z.TianA.Q.Hu)、小羊耳蒜(L.fargesii Finet)、条裂鸢尾兰(Oberonia jenkinsiana Lindley)、果香兰(Cymbidium suavissimum C.Curtis)和大花斑叶兰[Goodyera biflora(Lindley)J.D.Hooker],分别描述了每个物种的分类学特征,提供了相关的引证标本及地理分布信息,并附有彩色照片以供识别。 相似文献
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Tail autotomy, the self-induced tail separation from the body, is a common and effective antipredator mechanism in lizards. In this study, we examine the muscle energetics of tail shedding in six lacertid lizard species (Podarcis erhardii, Podarcis peloponnesiaca, Podarcis muralis, Podarcis gaigeae, Podarcis milensis, and Lacerta graeca) from the northeast Mediterranean region. Very long periods of postautotomy tail movement were demonstrated for all species (range=6-8 min), and differences among species were not statistically significant. Postautotomy tail movement, powered by anaerobic muscle activity, resulted in a strong increase in lactate concentrations and a concomitant depletion of muscle glycogen of exhausted tails relative to resting tails. No significant differences were found in either lactate or glycogen concentrations among the species examined. Duration of movement was negatively correlated with final lactate concentrations. The lack of differentiation in postautotomy energetic physiology in this group of species that have evolved under very different predation environments indicates that postautotomy muscle metabolism involves an overall conservative suite of characters. 相似文献
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Vasiliki Saroglou Petar D. Marin Ana Rancic Milan Veljic Helen Skaltsa 《Biochemical Systematics and Ecology》2007
The volatile composition of six Hypericum species has been studied. The essential oils were obtained by steam distillation in 500 mL H2O for 2 h in a modified Clevenger apparatus with a water-cooled oil receiver to reduce hydrodistillation over-heating artifacts, and their analyses were performed by GC and GC–MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. A total of 100 different compounds were identified. The main constituents of the investigated populations of each taxon have been revealed as follows: Hypericum alpinum: (−)-β-pinene, γ-terpinene, (−)-(E)-caryophyllene; Hypericum barbatum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum rumeliacum: (−)-α-pinene, (−)-β-pinene, (−)-limonene, Hypericum hirsutum: nonane, undecane, (−)-(E)-caryophyllene, (−)-caryophyllene oxide; Hypericum maculatum: spathulenol, globulol; Hypericum perforatum: (−)-α-pinene, (Z)-β-farnesene, germacrene D; Monoterpene hydrocarbons were shown to be the main group of the taxa belonging to the section Drosocarpium, while the taxa of section Hypericum were more rich in sesquiterpene hydrocarbons. 相似文献
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Two analogs of human beta-endorphin containing cystine bridges between positions 21 and 26 or 14 and 26 have been synthesized and their radioligand binding activity using rat brain membranes has been determined. Both peptides showed three to four times the binding activity of human beta-endorphin. 相似文献
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Rault M Mazzia C Capowiez Y 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2007,147(2):340-346
To validate cholinesterase activity as a biomarker of pesticide exposure, we characterized the tissue distribution (whole body, nervous tissue and crop/gizzard), activity at two seasons of cholinesterase in six different species of earthworms collected in an unpolluted field: Lumbricus terrestris, Lumbricus castaneus, Aporrectodea nocturna, Aporrectodea caliginosa, Allolobophora chlorotica and Aporrectodea rosea. The major part of total cholinesterase activity was found in the nervous tissue while activity in crop/gizzard was weak. The level of the total cholinesterase activity was stable for each species considered throughout the year (spring and autumn). Lumbricus species exhibited three-fold higher specific activity than the others (0.086+/-0.015 U mg(-1) and 0.235+/-0.036 U mg(-1) for Allolobophora or Aporrectodea, and Lumbricus species respectively). This stability of the base level makes cholinesterase activity a useful biomarker for monitoring effects of pesticide under natural conditions. Cholinesterase activity was characterized using different substrates and inhibitors. It seems likely that the cholinesterases are acetylcholinesterases in most species investigated as they preferentially hydrolyzed acetylthiocholine and were inhibited by eserine, but not by tetraisopropyl pyrophoramide (iso-OMPA). Characterization of cholinesterase from Allolobophora chlorotica is uncertain and it cannot be classified as a true AChE. 相似文献
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Maidment JM Moore D Murphy GP Murphy G Clark IM 《The Journal of biological chemistry》1999,274(49):34706-34710
Five genes potentially encoding novel matrix metalloproteinases (MMPs) have been identified on the Arabidopsis thaliana data base. The predicted proteins have a similar domain structure to mammalian MMP-7, with a propeptide and catalytic domain but no C-terminal hemopexin-like domain. Four of the A. thaliana MMPs (At-MMPs) have a predicted C-terminal transmembrane domain. The At-MMPs are differentially expressed in flower, leaf, root, and stem tissues from 14-day-old plants. The cDNA for one of the At-MMPs (At1-MMP) was cloned and expressed in Escherichia coli. Following refolding and purification, the proenzyme At1-MMP was shown to undergo autolytic activation in the presence of an organomercurial with a concomitant decrease in M(r). In contrast to this, trypsin-treatment led to the formation of an inactive product. The activated At1-MMP digested myelin basic protein, but was unable to digest gelatin or casein. Three peptide substrates for MMPs were also cleaved by At1-MMP. The enzyme activity of At1-MMP was inhibited by human tissue inhibitors of metalloproteinases 1 and 2 and the hydroxamate inhibitor BB-94. 相似文献
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Morphine, enkephalins, nalorphine, naloxone and pentazocine are shown to have a peripheral analgesic effect. In our modification of the Randall-Selitto test these substances were 50–100 times more potent than a standard local anaesthetic, lidocaine. At this peripheral site, naloxone did not antagonize the effect of morphine. Morphine had a marked analgesic effect on the hyperalgesia induced by PGE2 and PGI2, BaCl2, Ca2+ ionophore A23187, isoprenaline but not on that induced by dibutyryl cyclic AMP. It was suggested that the peripheral analgesic effect of morphine is due to an inhibition of adenylate-cyclase activity. 相似文献
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Role of peripheral and central opioid activity in analgesia induced by restraint stress 总被引:1,自引:0,他引:1
Rats subjected to prolonged restraint showed an increase in tail flick latency which outlasted the period of restraint by 15 min. This restraint could be blocked but not reversed by 1 mg/kg of naltrexone hydrochloride given subcutaneously. Naltrexone methobromide, administered subcutaneously in doses of 10 or 25 mg/kg, did not block the analgesia indicating that peripheral opioid receptors were probably not involved. Naltrexone hydrochloride was shown to have no effect on brain tryptophan uptake in restrained rats, a neurochemical event which had previously been shown to be critical to restraint-induced analgesia. 相似文献
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Cuticular alkanes obtained from larvae and adults of six species of tephritid fruit flies, Anastrepha ludens, A. suspensa, Ceratitis capitata, C. rosa, Dacus cucurbitae, and D. dorsalis were analyzed by gas chromatography. The same four major alkanes were shown to be present by capillary GC-mass spectra in all Anastrepha and Ceratitis larvae. Profiles were obtained from individual larvae and adult specimens that showed statistical differences between species, whereas profiles of conspecific life forms including pupae of A. suspensa from different locations showed some similarities. Sexual dimorphism was not observed in alkanes extracted from adults. A novel series of alkadienes was found in all Anastrepha and Ceratitis but not in Dacus. 相似文献
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报道了国产黄耆属(Astragalus)6种植物的染色体数目和核型。结果表明,这6种黄耆属植物均为二倍体,其核型公式分别为:甘青黄耆(A.tangutlcus),2n=16=6m 8sm 2t,“3A”核型;悬垂黄耆(A.dependens),2n=16=10m 6sm,“2A”核型;四川黄耆(A.sutchuenensis),2n=16=8m 8sm,“2A”核型;萨雷古拉黄耆(A.pavlovlanus),2n=16=12m 4sm,“1A”核型;喜石黄耆(A.petraeus),2n=16=14m 2sm,“1A”核型;拟糙叶黄耆(A.pseudoscaberrimus),2n=16=14m 2sm,“1A”核型。这6种黄耆属植物的染色体数目和核型均为首次报道。 相似文献
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Endophytic fungi were isolated from the stems, petioles, midribs, and leaves of seedlings of six native tree species collected from Doi Suthep-Pui National Park, Thailand. Endophytes were isolated from all tissue samples investigated, and taxa included five ascomycetes, eight anamorphic taxa, and numerous sterile mycelia. Twenty-six strains were tested for their ability to produce cellulase, mannanase, proteinase, and xylanase. The ability to produce these enzymes was distributed amongst the strains tested. Rainforest seedlings supported a diverse array of endophytes that have a wide range of enzymatic activities. The implication of enzyme production in relation to lifestyle abilities of the endophytes is discussed. 相似文献
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Morphine, enkephalins, nalorphine, naloxone and pentazocine are shown to have a peripheral analgesic effect. In our modification of the Randall-Selitto test these substances were 50--100 times more potent than a standard local anaesthetic, lidocaine. At this peripheral site, naloxone did not antagonize the effect of morphine. Morphine had a marked analgesic effect on the hyperalgesia induced by PGE2 and PGI2, BaCl2, Ca2+ ionophore A23187, isoprenaline but not on that induced by dibutyryl cyclic AMP. It was suggested that the peripheral analgesic effect of morphine is due to an inhibition of adenylate-cyclase activity. 相似文献
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Abstract.
- 1 Two contrasting hypotheses concerning patterns in food web structure within pitchers of Nepenthes are tested using new information from six species of Nepenthes from Borneo.
- 2 In general, predictions that webs will be more complex, and the food chains they contain will be longer, the closer they are to the centre of Nepenthes species diversity, are supported.
- 3 For Nepenthes albomarginata, a widespread species with a distinctive north Bornean form, a contrasting pattern is evident explicable in terms of the morphology of the pitchers and local habitat preferences.
- 4 General explanations for food web patterns will always be susceptible to exception, reflecting nuances of natural history.