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J Shobha B Bhattacharyya D Balasubramanian 《Journal of biochemical and biophysical methods》1989,18(4):287-295
Enhancement of the fluorescence intensity of colchicine occurs in media of low polarity and appreciable viscosity; this is suggested to be the basis of the intensification of its fluorescence when it is bound to and immobilized in tubulin. We show here that the tubulin-bound fluorescence features of colchicine are largely reconstructed upon solubilizing it in chosen micellar aggregates that offer optimal polarities and microviscosities. Triton X-100 and bile salt micelles intensify the colchicine emission but the maximal effects are obtained with tetrameric aggregates of the peptide melittin. Estimates of the polarity, microviscosity and binding-site dimensions of colchicine are obtained using this mimetic approach. Our results suggest that well chosen micellar systems act as good models to reconstruct and analyze the spectral properties of molecules immobilized in their binding sites. 相似文献
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Tubulin subunit carboxyl termini determine polymerization efficiency 总被引:21,自引:0,他引:21
Cleavage of tubulin by subtilisin removes a small (Mr less than 2000) fragment from the C-terminal end of both alpha and beta subunits. The resulting protein is much reduced in negative charge. The cleaved, less acidic protein retains its competence to polymerize in a GTP-dependent and cold-, GDP-, and podophyllotoxin-sensitive manner and assembles into sheets or bundles of twisted filaments. The critical concentration for polymerization of the cleaved protein is about 50-fold lower than that for intact tubulin. It is proposed that the C termini of the subunits normally impede polymerization. 相似文献
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Bodhendu B. Gupta Anjan Bhattacharyya Santi R. Mitra Narayan Adityachaudhury 《Phytochemistry》1983,22(5):1306-1307
The pods of Milletia auriculata have yielded a new substance, 5,7-dihydroxy-6-methoxy-4′-O-prenyloxyisoflavone. 相似文献
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Summary The effect of different concentrations of CO2 on the germination of conidiospores of Aspergillus niger A 5 has been studied using Pardee's buffer mixtures which maintain constant CO2 tensions. The beneficial effect of CO2 on germination is maximum at 0.5% CO2 concentration, when 70–90% of the spores germinate within 6 hours, whereas in controls with air containing 0.03% CO2 there is only 15–20% germination at 6 hours. At higher CO2 concentrations this beneficial effect of CO2 on germination diminishes and at 3% there is a complete inhibition of spore germination.The spore density and the ph of the medium have a noticeable effect on germination rates in presence of 0.5% CO2. The germination rates decrease at spore densities higher than 5 · 105/ml and at a ph of 6.8.Communication No. 431. 相似文献
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Abstract A highly sensitive nested polymerase chain reaction method was designed for the detection of a wide spectrum of strains from Borrelia burgdorferi sensu lato. This technique allows the detection of as little as 3 fg of total genomic DNA extracted and purified from pure cultures of the organism, this amount corresponds to less than 10 organisms. Two sets of primers homologous to conserved spots in the coding region of the hbb gene, encoding a conserved histone-like protein, were constructed. These were based on a multiple sequence alignment of 39 strains representing all the genomic groups described in B. burgdorferi sensu lato. 相似文献
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