http://nopr.niscair.res.in/handle/123456789/3452 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3537 Title: Effect of exogenous sucrose on the enzymes of starch degradation and sucrose metabolism in cowpea (Vigna unguiculata L.) seedlings <br/> <br/>Authors: Kaur, Narinder; Kaur, Harpreet; Gupta, Anil K <br/> <br/>Abstract: Addition of exogenous sucrose and mannitol in the growth medium decreased the germination and growth of cowpea (Vigna unguiculata L. cv C-88) seedlings. The reduced seedling growth appeared to be due to the decreased acid invertase activity in growing parts of the seedlings. An exogenous supply of sucrose upregulated the sucrose phosphate synthase (SPS) activity in different parts of seedlings. Decreased amylase activity in cotyledons and the mobilization of starch from cotyledons to the growing axis was observed in the presence of exogenous sucrose and mannitol. High sucrose content observed in different tissues in the presence of exogenous sucrose and mannitol was possibly due to high SPS and low acid invertase activities and reduced conversion of sucrose to starch. It appears that exogenous sucrose acts mainly as an osmoticum, rather than a source of carbon for the growing seedlings. <br/> <br/>Page(s): 295-300 Wed, 28 Sep 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3536 Title: QSAR analysis of 2,4-diaminopyrido[2,3-d]pyrimidines and 2,4-diaminopyrrolo[2,3-d]pyrimidines as dihydrofolate reductase inhibitors <br/> <br/>Authors: Jain, P; Soni, L K; Gupta, A K; Kashkedikar, S G <br/> <br/>Abstract: Dihydrofolate reductase (DHFR) plays a ubiquitous role in the biosynthesis of DNA, RNA and essential amino acid methionine, and exhibits potential application in the treatment and prophylaxis of AIDS-associated opportunistic microbial infections. In this study, a series of DHFR analogs of 2,4-diaminopyrido[2,3-d]pyrimidines and 2,4-diaminopyrrolo[2,3-d]pyrimidines were subjected to quantitative structure-activity relationship (QSAR) analysis. The results showed that the electronic properties, energy of lowest unoccupied molecular orbital (LUMO) and Z-component of dipole moment (DPL₃) of the molecule could be explored to design the potent DHFR inhibitors. LUMO is indicative of π-bonding interaction of species crucial for the electrophilicity of the molecules. This suggests that molecules are able to interact with electron-rich area at the receptor site. DPL₃ is related to the molecular charge distribution in Z-component. These electronic parameters can be altered through the incorporation of electronegative groups. The QSAR study provides important structural insights for designing the potent DHFR inhibitors. <br/> <br/>Page(s): 315-320 Wed, 28 Sep 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3534 Title: Analysis of solid-phase allele-specific primer extension characteristics on biochip in combination with modified primers and PicoGreen staining method <br/> <br/>Authors: Qin, Shengying; Liu, Jianhua <br/> <br/>Abstract: DNA microarray technology offers potential for future high-throughput variation genotyping. Allele-specific primer extension procedure on microarray has been considered as an efficient method for single nucleotide polymorphism (SNP) genotyping. However, the high cost of the fluorescent-labeled dNTP used for signal detection in this method limits its application. In the present study, we evaluated the characteristics of solid-phase allele-specific primer extension, in terms of specificity and efficiency and demonstrated that compared to liquid-phase reaction, it requires lower annealing temperature, and higher template and Mg²⁺concentrations. The extension efficiency and specificity were though linked, behave diametric during the gradient change of template and Mg²⁺concentrations or annealing temperature. To obtain both optimal signal intensity and specificity, we introduced an artificial mismatched base at the third position from the primer 3′end, which enhanced the specificity significantly. The PicoGreen staining method, which could decrease the cost greatly, was then introduced to replace the fluorescent-labeled dNTP for signal detection. <br/> <br/>Page(s): 308-314 Wed, 28 Sep 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3533 Title: Thermodynamic study of magnesium ion binding to ⍺-amylase <br/> <br/>Authors: Saboury, Ali Akbar; Ghasemi, Setareh; Dahot, Mohammad Umar <br/> <br/>Abstract: The interaction of -amylase (from Bacillus amyloliquefaciens) with Mg²⁺ ion was studied using UV spectrophotometric and isothermal titration calorimetric (ITC) methods at 27ºC in 30 mM Tris buffer solution at pH = 7.0. The binding isotherm for metal-protein interaction was easily obtained by carrying out ITC experiment at two different concentrations (2 μM and 50 μM) of the protein. ⍺-Amylase had eight identical and independent binding sites for Mg²⁺ ion, which showed non-cooperativity in the binding process. The binding of Mg²⁺ ion was exothermic (ΔH= 17.3 kJ mol⁻¹) with association binding constant of 2.08 mM⁻¹. The binding slightly destabilized the enzyme against thermal denaturation, as evident from absorption studies. <br/> <br/>Page(s): 326-329 Wed, 28 Sep 2005 22:58:59 GMT