کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7786656 1500622 2016 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Properties of a glycogen like polysaccharide produced by a mutant of Escherichia coli lacking glycogen synthase and maltodextrin phosphorylase
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Properties of a glycogen like polysaccharide produced by a mutant of Escherichia coli lacking glycogen synthase and maltodextrin phosphorylase
چکیده انگلیسی
Escherichia coli mutant TBP38 lacks glycogen synthase (GlgA) and maltodextrin phosphorylase (MalP). When grown on maltose in fed-batch fermentation TBP38 accumulated more than 50-fold higher glycogen-type polysaccharide than its parental strain. The polysaccharides were extracted at different growth stages and migrated as one peak in size-exclusion chromatography. TBP38 produced polysaccharides ranging 2.6 × 106-4.6 × 106 Da. A ratio of short side-chains (DP ≦ 12) in the polysaccharides was greater than 50%, and number-average degree of polymerization varied from 9.8 to 8.4. The polysaccharides showed 70-290 times greater water-solubility than amylopectin. Km values using porcine and human pancreatic α-amylases with polysaccharides were 2- to 4-fold larger than that of amylopectin. kcat values were similar for both α-amylases. The TBP38 polysaccharides had 40-60% lower digestibility to amyloglucosidase than amylopectin. Intriguingly, the polysaccharides showed strong immunostimulating effects on mouse macrophage cell comparable to lipopolysaccharides. The lipopolysaccharide contamination levels were too low to account for this effect.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Polymers - Volume 136, 20 January 2016, Pages 649-655
نویسندگان
, , , , , , ,