The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements...The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements and cyclic voltammetry. The apparent binding constant of vitamin B12 with DNA was found to be 3.2 × 10^5 mol^-1·L. The voltammetric behavior of vitamin B12 has been investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including △H^0, △S^0 and △G^0 for the interaction between VB12 and DNA have determined as -2.3 × 10^4, 27.54 and -3.1 × 10^4j·mol^-l·K^-1 respectively. One indication of DNA binding mode with VBI2 was the change in viscosity when a small molecule associates with DNA. The diffusion coefficients of VB12 in the absence （D0）f and presence of DNA （D0）b was calculated as 5.04 × 10^-6 and 1.13 × 10^-6 cm^2·s^-1 respectively. The results indicated that vitamin B12 can bind to DNA and the major binding mode was intercalative binding.展开更多
The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the a...The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight. The copolymer was characterized by using Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H-NMR） analyses. The molecular weight distributions were evaluated by Mv/Mn ratios estimated from viscosity and osmotic measurements, and Mw/Mn estimated from size exclusion chromatography. The molecular weight distributions of these polymers as determined from M, JMn and Mw/Mn are 2.9 to 3,2 and 2.0 to 2.5 respectively. The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0. Intrinsic viscosity [η] as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography （SEC-LALLS） and viscometry with SEC （SEC-VISCO）. The relationship between [η] and Mw for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃ was [q] = 1.1×10-5 Mw0.79, where [η] is obtained in dL/g.展开更多
文摘The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements and cyclic voltammetry. The apparent binding constant of vitamin B12 with DNA was found to be 3.2 × 10^5 mol^-1·L. The voltammetric behavior of vitamin B12 has been investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including △H^0, △S^0 and △G^0 for the interaction between VB12 and DNA have determined as -2.3 × 10^4, 27.54 and -3.1 × 10^4j·mol^-l·K^-1 respectively. One indication of DNA binding mode with VBI2 was the change in viscosity when a small molecule associates with DNA. The diffusion coefficients of VB12 in the absence （D0）f and presence of DNA （D0）b was calculated as 5.04 × 10^-6 and 1.13 × 10^-6 cm^2·s^-1 respectively. The results indicated that vitamin B12 can bind to DNA and the major binding mode was intercalative binding.
基金financially supported by the Council of Scientific and Industrial Research,New Delhi under Supra Institutional Project(SIP-IFCAP-04)
文摘The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight. The copolymer was characterized by using Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H-NMR） analyses. The molecular weight distributions were evaluated by Mv/Mn ratios estimated from viscosity and osmotic measurements, and Mw/Mn estimated from size exclusion chromatography. The molecular weight distributions of these polymers as determined from M, JMn and Mw/Mn are 2.9 to 3,2 and 2.0 to 2.5 respectively. The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0. Intrinsic viscosity [η] as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography （SEC-LALLS） and viscometry with SEC （SEC-VISCO）. The relationship between [η] and Mw for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃ was [q] = 1.1×10-5 Mw0.79, where [η] is obtained in dL/g.
