Study On Synthesis Of Galactooligosaccharide By Lactase

Galactoligosaccharides(GOS)are recognized as one of the most important functional oligosaccharides,and their molecular structure is generally on one side of the lactose molecule to beta(1?3),beta(1?4),beta(1?6)glycosidic bond connecting 1-7 galactose medium.they have received widely attention because of their superior physiological function.The research used the ?-galactosidase from Kluyveromyces lactis to synthesis galactooligosaccharides from lactose.Qualitative analysis by TLC and quantitative analysis by HPLC-ELSD were used to research GOS,and optimize the synthesis conditions;and try to separation and purification of galactoligosaccharides by amino chromatography column,ion-exchange resin,sllica gel column;the molecular weight of the isolated product was analyzed by ESI-MS,the degree of polymerization was determined by molecular weight.1.Experimental results show that TLC can confirm the occurrence of a reaction,TLC can qualitative analysis of galactooligosaccharides.The solvent system was butanol: ethanol:water=5:3:2,developer was 1g N-phenylaniline,1m L aniline,1m L phosphoric acid soluble in 50 m L acetone.JASCO N2000 ELSD could used to quantitative analysis of galactooligosaccharides.Chromatographic condition: amino chromatography column(Spherisord 5?m NH24.6×250mm)held at 35 ?,mobile phase was acetonitrile:water=80:20,flow rate was1.0m L/min,Sample volume was 20 ?L,ELSD held at 80?,gas rate was 2.0m L/min.2.The optimum synthesis conditions were: substrate(lactose)concentration 40%,the amount of enzyme 40 U/g,p H7.5,5 ?,2 h,under the optimum conditions,galactooligosaccharides yield reached 23.4%.3.The sample was detectied by ESI-MS.The molecular weights of the two groups were527 and 689,respectively.The degree of polymerization was 3 and 4.The two components were galactooligostrisaccharides and galactooligostetroseaccharides.The trisaccharides has two hexose units linked by a ?(1?4)linkagethis tretramer had a ?(1?4)linkage at the reducing end and two other ?(1?6)linkages.4.Separation condition of silica gel column height was 300 mm,normal pressure,natural flow rate elution,sample volume 2 g,The solvent system was butanol: ethanol:water=5:3:2.