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四氢蒽醌类化合物是一类比较少见的天然结构,以微生物次生代谢产物居多,少量来源于植物,具有细胞毒活性、抗菌活性、抗疟原虫等生物活性。本文主要从四氢蒽醌类化合物及其衍生物的结构和生物活性两方面来对天然四氢蒽醌化合物进行综述,共综述了54个四氢蒽醌类化合物,45个来源于微生物,9个来源于植物南山花的根中,其中altersolanol A具有很好的抗肿瘤活性,是一个有很大吸引力的抗癌先导化合物。通过对四氢蒽醌类化合物的综述,为四氢蒽醌类化合物的进一步研究和开发提供依据。 相似文献
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The action of trypsin at 55 degree C and pH 8.3 on pig IgM anti-Salmonella has been compared with the action of pepsin at 37 degree C and pH 4.6. Both processes cause the gradual removal of Fab arms and Cmu2 domains to produce eventually an (Fc)5 fragment. However, during tryptic digestion Fab arms are preferentially removed from the same subunit, whereas peptic digestion causes random removal from any subunit. At intermediate stages of digestion both processes produce partially fragmented molecules which consist of an (Fc)5 portion still attached to limited numbers of Fab arms. Both processes cause a gradual decrease in the ability of molecules to agglutinate Salmonella, but complement fixation by the complexes declines much more rapidly. A stage is reached where molecules having four Fab arms can still agglutinate but there is no complement fixation. However, the remaining arms on the tryptic molecules are distributed in pairs on the same subunit, whereas those on the peptic molecules are distributed randomly. Hence the number of remaining Fab arms, rather than their distribution, appears to be the critical factor which influences biological activity. A possible explanation for this is discussed. 相似文献
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Over eighty compounds have been assayed for fungistatic activity. Fusarium graminearum, Penicillium digitatum and Botrytis allii were used as test organisms. The preliminary results suggest that fungistatic activity is associated with the tendency of the substituents to withdraw electrons from the double bond. Nitroethylenes and fumarates are, for example, fungistatic. Tetraiodoethylene has high activity but this can hardly be attributed solely to the withdrawal of electrons from the double bond by the iodine atoms. 相似文献
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Amino acids are transported across the human placenta mediated by transporter proteins that differ in structure, mechanism
and substrate specificity. Some of them are Na+-dependent systems, whereas others are Na+-independent. Among these there are transporters composed of a heavy chain, a glycoprotein, and a light chain. Moreover, they
can be differently distributed in the two membranes forming the syncytiotrophoblast. The transport mechanisms involved and
their regulation are only partially known. In the placenta itself, part of the amino acids is metabolized to form other compounds
important for the fetus. This occurs for instance for arginine, which gives rise to polyamines and to NO. Interconversion
occurs among few other amino acids Transport is altered in pregnancy complications, such as restricted fetal growth. 相似文献
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Alessandra V.R. da Silva Bibiana M. De Souza Marcia P. dos Santos Cabrera Nathalia B. Dias Paulo C. Gomes João Ruggiero Neto Rodrigo G. Stabeli Mario S. Palma 《生物化学与生物物理学报:生物膜》2014
Polycationic peptides may present their C-termini in either amidated or acidic form; however, the effects of these conformations on the mechanisms of interaction with the membranes in general were not properly investigated up to now. Protonectarina-MP mastoparan with an either amidated or acidic C-terminus was utilized to study their interactions with anionic and zwitterionic vesicles, using measurements of dye leakage and a combination of H/D exchange and mass spectrometry to monitor peptide–membrane interactions. Mast cell degranulation, hemolysis and antibiosis assays were also performed using these peptides, and the results were correlated with the structural properties of the peptides. The C-terminal amidation promotes the stabilization of the secondary structure of the peptide, with a relatively high content of helical conformations, permitting a deeper interaction with the phospholipid constituents of animal and bacterial cell membranes. The results suggested that at low concentrations Protonectarina-MP interacts with the membranes in a way that both terminal regions remain positioned outside the external surface of the membrane, while the α-carbon backbone becomes partially embedded in the membrane core and changing constantly the conformation, and causing membrane destabilization. The amidation of the C-terminal residue appears to be responsible for the stabilization of the peptide conformation in a secondary structure that is richer in α-helix content than its acidic congener. The helical, amphipathic conformation, in turn, allows a deeper peptide–membrane interaction, favoring both biological activities that depend on peptide structure recognition by the GPCRs (such as exocytosis) and those activities dependent on membrane perturbation (such as hemolysis and antibiosis). 相似文献
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M. H. Abd-Alla 《Folia microbiologica》1994,39(1):57-60
Azotobacter chroococcum was isolated from straw-amended soil and found to utilize 4-hydroxybenzoic acid, resorcinol, pyrocatechol and vanillic acid
as sole carbon source. Growth and nitrogenase activity ofA. chroococcum were supported by 8, 6 and 4 mmol/L of 4-hydroxybenzoic acid, resorcinol and pyrocatechol, respectively. The generation time
of 1.71 h in 4-hydroxybenzoic acid did not significantly differ from the generation time of 1.64 h, observed when grown in
mannitol. 4-Hydroxybenzoic acid was utilized rapidly. However, the decomposition of other tested phenolic compounds set in
only slowly. It was concluded that this isolate has good potential to utilize some phenolic compounds released during biodegradation
of plant wastes. 相似文献
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P-coumaric acid (HCA), 2,4-dichlorophenol (DCP) and resorcionol acted as cofactors for IAA-oxidase isolated from young wheat plants. Ferulic acid (FA) and 3,4-dihydroxybenzoic acid (DHBA) induced a lag phase prior to IAA oxidation. HCA, FA (0.2-1 mg ml-1) and DCP (0.03-1 mg ml-1) strongly inhibited wheat coleoptile section growth. DHBA (0.01-1 mg ml-1) slightly stimulated it and resorcinol was without effect. HCA inhibited IAA-induced growth of coleoptile sections and FA stimulated it at low IAA levels and inhibited it at higher ones. DHBA, DCP and resorcinol did not affect IAA-induced growth of coleoptile sections. 相似文献
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A. J. Sexton A. Loesch M. Turmaine S. Miah G. Burnstock 《Cell and tissue research》1996,284(1):167-175
Human umbilical vessels are devoid of nerves and therefore endothelial cells may play an important role in the control of
feto-placental blood flow. The pharmacological effects of 5-hydroxytryptamine, histamine and endothelin were examined in umbilical
arteries and veins from legal terminations (gestational age 8–17 weeks, n=12) and normal term vaginal deliveries (gestational age 38–41, n=12). Immunocytochemistry of human unbilical vessels indicated that 5-hydroxytryptamine, histamine and endothelin were localised
in subpopulations of endothelial cells of both artery and vein in late, but not early, pregnancy. 5-Hydroxytryptamine (10
nM–30 μM) caused sustained concentration-dependent contractions in all vessels from early and late pregnancy. Histamine (0.1
μM–30 mM) also caused sustained contractions in all vessels from late pregnancy but only 27% of arteries and 41% of veins
from early pregnancy responded. Endothelin (10 pM–30 nM) caused slow long-lasting contractions in all vessels from early and
late pregnancy. Atrial natriuretic peptide and neuropeptide Y did not alter vascular tone. The endothelium may thus play an
autocrine/paracrine role, by synthesizing and releasing the above reactive substances in late pregnancy to influence feto-placental
blood flow.
Received: 23 May 1995 / Accepted: 13 October 1995 相似文献
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Matousek J Gotte G Pouckova P Soucek J Slavik T Vottariello F Libonati M 《The Journal of biological chemistry》2003,278(26):23817-23822
Dimers, trimers, and tetramers of bovine ribonuclease A, obtained by lyophilization of the enzyme from 40% acetic acid solutions, were purified and isolated by cation exchange chromatography. The two conformers constituting each aggregated species were assayed for their antitumor, aspermatogenic, or embryotoxic activities in comparison with monomeric RNase A and bovine seminal RNase, which is dimeric in nature. The antitumor action was tested in vitro on ML-2 (human myeloid leukemia) and HL-60 (human myeloid cell line) cells and in vivo on the growth of human non-pigmented melanoma (line UB900518) transplanted subcutaneously in nude mice. RNase A oligomers display a definite antitumor activity that increases as a function of the size of the oligomers. On ML-2 and HL-60 cells, dimers and trimers generally show a lower activity than bovine seminal RNase; the activity of tetramers, instead, is similar to or higher than that of the seminal enzyme. The growth of human melanoma in nude mice is inhibited by RNase A oligomers in the order dimers < trimers < tetramers. The action of the two tetramers is very strong, blocking almost completely the growth of melanoma. RNase A dimers, trimers, and tetramers display aspermatogenic effects similar to those of bovine seminal RNase, but, contrarily, they do not show any embryotoxic activity. 相似文献
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LUSCHINSKY HL 《Archives of biochemistry and biophysics》1951,31(1):132-140
Homogenates and extracts of human placenta are able to desamidate glutamine by means of an enzyme which has the properties of glutaminase. Placental glutaminase is activated by phosphate. Its pH optimum lies at 9.0.A method for its assay in placental homogenate is described. It was found that the glutaminase activity decreases toward the end of pregnancy. At this time, the activity, expressed as QNH3 (N), amounts to 23.7 ± 6.7.Some quantitative aspects of glutaminase activity in the human placenta and kidney are discussed. 相似文献
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聚乙二醇对PEG化重组人促红细胞生成素热稳定性和生物学活性的影响 总被引:1,自引:0,他引:1
为了研究聚乙二醇对PEG化rhEPO热稳定性和生物学活性的影响,用酶学方法切除rhEPO和PEGrhEPO分子中的N连接糖基,研究酶切产物在37℃时287nm和350nm吸光度随时间的变化;用MTT比色法,网织红细胞法和HCT法比较体内和体外生物学活性的改变。结果显示聚乙二醇修饰能显著减少无N连接糖基的rhEPO分子间的聚集,降低rhEPO体外生物学活性,但增高体内生物学活性;无N连接糖基的PEG化rhEPO具有与rhEPO相当的体内生物学活性。因此聚乙二醇能提高rhEPO热稳定性;聚乙二醇可替代糖基,维持rhEPO的体内生物学活性。用PEG修饰原核细胞表达的rhEPO是开发rhEPO制品的新思路。 相似文献
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Paul Arenz Lemke 《Mycopathologia》1969,38(1-2):49-59