In order to study the effects of different extraction methods on the molar mass distribution and chain conformation of Fortunella margarita （Lour.） Swingle polysaccharides （FP）, we used extraction by hot water （...In order to study the effects of different extraction methods on the molar mass distribution and chain conformation of Fortunella margarita （Lour.） Swingle polysaccharides （FP）, we used extraction by hot water （WFP）, ultrasonic-assisted treatment （UFP）, microwave-assisted treatment （MFP） and ultrasonic/microwave-assisted treatment （UMFP）, and then Fourier transform infrared （FT-IR） spectroscopy as well as 1H and 13C nuclear magnetic resonance （NMR） spectroscopy to characterize the structural properties of FP extracted. The molar weight （Mw）, polydispersity index （Mw/Mn）, root-mean-square （RMS） turning radius （Rg）, molar mass distribution and chain conformation of FP were studied systematically using size-exclusion chromatography （SEC）, multi-angle laser light-scattering （MALLS） and refractive index （RI）. WFP, UFP, MFP and UMFP are all typical carbohydrates according to 1H NMR, laC NMR and FT-IR measurements. The type of glycosidic linkage is mainly a fl-glycosidic bond with a small amount of a-glycosidic bond. The results obtained by the SEC-MALLS-RI system showed the molar masses of WFP and UMFP were distributed mainly in the range of 5.0x10^6-1.0x10^7 g-mo1-1 and they accounted for 57.80% and 56.84% of total FP, respectively. The molar masses of UFP and MFP were distributed mainly in the 1.0x10^6-5.0x10^6 g.mol-1 range, which accounted for 38.24% and 52.39% of FP, respectively. WFP and UMFP in water were uniform spherical polymers; UFP and MFP were typical highly branched polymers and the degree of branching for MFP was higher compared to UFP. These results indicated the ultrasonic- and microwave-assisted extraction methods caused a significant decrease of the molar mass of FP but the ultrasonic/microwave synergistic extraction method had no effect.展开更多
The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective...The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective cleavages of the peptide bonds at Ash 3- Gin 4, His 5-Leu 6, Gly 8-Ser 9, and Glu 21-Arg 22 of oxidized insulin B chain.展开更多
The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which le...The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which lead to the selective cleavages of the peptide bonds at Phe1-Val2, His5-Leu6, Glu21-Arg22, and Arg22-Gly23 of oxidized insulin B chain.展开更多
基金Supported by Science and Technology Plan Major Project of Fujian Province(2013Y0003)Agricultural Products(fruits and vegetables) Processing Engineering Technology Research Center Funding Projects of Fujian Province(2009N2002)+1 种基金Scientific and Technological Innovation Team Support Plan of Institution of Higher Learning in Fujian Province([2012]03)Scientific and Technological Innovation Team Support Plan of Fujian Agriculture and Forestry University(cxtd12009)
文摘In order to study the effects of different extraction methods on the molar mass distribution and chain conformation of Fortunella margarita （Lour.） Swingle polysaccharides （FP）, we used extraction by hot water （WFP）, ultrasonic-assisted treatment （UFP）, microwave-assisted treatment （MFP） and ultrasonic/microwave-assisted treatment （UMFP）, and then Fourier transform infrared （FT-IR） spectroscopy as well as 1H and 13C nuclear magnetic resonance （NMR） spectroscopy to characterize the structural properties of FP extracted. The molar weight （Mw）, polydispersity index （Mw/Mn）, root-mean-square （RMS） turning radius （Rg）, molar mass distribution and chain conformation of FP were studied systematically using size-exclusion chromatography （SEC）, multi-angle laser light-scattering （MALLS） and refractive index （RI）. WFP, UFP, MFP and UMFP are all typical carbohydrates according to 1H NMR, laC NMR and FT-IR measurements. The type of glycosidic linkage is mainly a fl-glycosidic bond with a small amount of a-glycosidic bond. The results obtained by the SEC-MALLS-RI system showed the molar masses of WFP and UMFP were distributed mainly in the range of 5.0x10^6-1.0x10^7 g-mo1-1 and they accounted for 57.80% and 56.84% of total FP, respectively. The molar masses of UFP and MFP were distributed mainly in the 1.0x10^6-5.0x10^6 g.mol-1 range, which accounted for 38.24% and 52.39% of FP, respectively. WFP and UMFP in water were uniform spherical polymers; UFP and MFP were typical highly branched polymers and the degree of branching for MFP was higher compared to UFP. These results indicated the ultrasonic- and microwave-assisted extraction methods caused a significant decrease of the molar mass of FP but the ultrasonic/microwave synergistic extraction method had no effect.
文摘The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective cleavages of the peptide bonds at Ash 3- Gin 4, His 5-Leu 6, Gly 8-Ser 9, and Glu 21-Arg 22 of oxidized insulin B chain.
文摘The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which lead to the selective cleavages of the peptide bonds at Phe1-Val2, His5-Leu6, Glu21-Arg22, and Arg22-Gly23 of oxidized insulin B chain.
