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We describe antigens of Plasmodium falciparum recognised by murine monoclonal antibodies which by immunofluorescence react with the rhoptry organelles of the extracellular merozoite stage. Immunoblotting shows that the antibodies recognise two major parasite antigens of Mr 82 and 65 kilodaltons (kDa). Immunoprecipitations from detergent extracts of [35S]-methioninelabelled parasites show that the 82-kDa and 65-kDa antigens are parasite proteins. Pulse-chase experiments on synchronous parasite cultures show that the 82-kDa protein is synthesised during early schizogony and is later processed into the 65-kDa antigen in segmenting schizonts. In Nonidet P-40, these antigens are non-covalently associated with two other proteins of 40 kDa and 42 kDa. The 40/42-kDa doublet is synthesised in parallel with the 82 kDa antigen and persists, apparently unchanged, till the end of the cell cycle.Abbreviations
HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
-
EDTA
ethylenediaminetetraacetic acid
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EGTA
ethyleneglycolbis-(aminoethylether) tetraacetic acid
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PMSF
phenylmethylsulphonylfluoride
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TLCK
tosyl-L-lysine chloromethyl ketone
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SDS-PAGE
sodium dodecyl sulphate polyacrylamide gel electrophoresis
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M
r
relative molecular mass 相似文献
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999.
Mukherjee R Kumar V Srivastava SK Agarwal SK Burman AC 《Anti-cancer agents in medicinal chemistry》2006,6(3):271-279
Betulinic acid, a pentacyclic triterpene, is widely distributed throughout the tropics. It possesses several biological properties such as anticancer, anti-inflammatory, antiviral, antiseptic, antimalarial, spermicidal, antimicrobial, antileshmanial, antihelmentic and antifeedent activities. However, betulinic acid was highly regarded for its anticancer and anti-HIV activities. Anticancer role of betulinic acid appeared by inducing apoptosis in cells irrespective of their p53 status. Due to high order safety in betulinic acid, a number of structural modifications carried out to improve its potency and efficacy. The C-1, C-2, C-3, C-4, C-20 and C-28 positions are the diversity centers in betulinic acid, and the derivatives resulted on various structural modifications at these positions screened for their anticancer activity. This review presents the structure activity relationship carried out on C-1, C-2, C-3, C-4, C-20, C-28, A-ring, D-ring and E-ring modified betulinic acid derivatives. We have compiled the most active betulinic acid derivatives along with their activity profile in each series. Structure activity relationship studies revealed that C-28 carboxylic acid was essential for the cytotoxicity. The halo substituent at C-2 position in betulinic acid enhanced the cytotoxicity. Though the relation of the cytotoxicity with the nature of substituents at C-3 position could not be generalized but the ester functionality appeared to be a better substituent for enhancing the cytotoxicity. An interesting observation is that the three rings skeleton (A, B and C rings) had played an important role in eliciting anticancer activity, which could be a new molecular skeleton to design new anticancer drugs. 相似文献
1000.
Sinha AK Anand S Ortel BJ Chang Y Mai Z Hasan T Maytin EV 《British journal of cancer》2006,95(4):485-495
Photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) to drive production of an intracellular photosensitiser, protoporphyrin IX (PpIX), is a promising cancer treatment. However, ALA-PDT is still suboptimal for thick or refractory tumours. Searching for new approaches, we tested a known inducer of cellular differentiation, methotrexate (MTX), in combination with ALA-PDT in LNCaP cells. Methotrexate alone promoted growth arrest, differentiation, and apoptosis. Methotrexate pretreatment (1 mg l(-1), 72 h) followed by ALA (0.3 mM, 4 h) resulted in a three-fold increase in intracellular PpIX, by biochemical and confocal analyses. After exposure to 512 nm light, killing was significantly enhanced in MTX-preconditioned cells. The reverse order of treatments, ALA-PDT followed by MTX, yielded no enhancement. Methotrexate caused a similar relative increase in PpIX, whether cells were incubated with ALA, methyl-ALA, or hexyl-ALA, arguing against a major effect upon ALA transport. Searching for an effect among porphyrin synthetic enzymes, we found that coproporphyrinogen oxidase (CPO) was increased three-fold by MTX at the mRNA and protein levels. Transfection of LNCaP cells with a CPO-expressing vector stimulated the accumulation of PpIX. Our data suggest that MTX, when used to modulate intracellular production of endogenous PpIX, may provide a new combination PDT approach for certain cancers. 相似文献